If you’re not sure of the differences between USB-C vs. Thunderbolt (3) or between USB 3.0 vs. USB 3.2, you’re not alone.
But mind you, we’ve been in a pretty good place for a couple of years now. Not so long ago, we had to also deal with a myriad of other peripheral connections types, like Parallel, Serial, FireWire, eSATA, and so on.
This post will help you understand the current state of modern connection standards — namely USB and Thunderbolt — so that you can plug one device into another with confidence.
There are two things to keep in mind in laymen’s terms: connection type and connection standard. Let’s start with the type.
Dong’s note: I first published this post on November 13, 2019, and updated it on August 5, 2021, with additional up-to-date information.
1. Connection type: How things fit
We generally use a cable to connect a device (like a portable drive) to a host (like a computer). This cable, like all cables, has two ends, which are male connectors or connectors for short.
One end goes into a host, and the other goes into the device itself. The holes the cable’s ends plug into are female ports or ports for short. The configuration of a port determines its type. Each port type has its corresponding connector.
USB-C port type is the new norm
Most modern devices use USB Type-C (or USB-C for short) port type.
In this case, both ends of the connecting cable are the same; they are USB-C connectors. It’s super convenient — you don’t need to figure out which end of the wire goes into the host and which is for the device.
The USB-C port also features reversible plug orientation, meaning you can plug the cable in with whichever side up or down.
What’s more, USB-C also works as the power connector for large devices, like a laptop — the machine won’t need a dedicated power port anymore — and it can deliver power both ways. So, for example, when connecting two smartphones using a USB-C cable, you can share data and power between them.
This convenience is available to the latest USB standard and Thunderbolt 3, which also uses USB-C port type.
(I’m aware of Thunderbolt 4, as you’ll note in the Connection Standard section below, but stay with me! You’ll understand why TB3 is more significant by the end of this section.)
In other words, when all of our devices support USB-C, which is the way of the future, there’s no need to worry about what cable to carry anymore since there’s just one type of cable.
Well, almost. Unfortunately, things are more complicated than that. For one, thunderbolt and USB are not fully compatible.
Port types: Thunderbolt 3 vs. USB-C
All Thunderbolt 3 ports work as a USB-C port, but not vice versa. As a result, you can plug a USB-C portable drive into a TB3 port, and it will work as intended.
However, a TB3-only device, like the Samsung X5 portable drive, will not work when plugged into a USB-C port, even though its cable fits perfectly. The reason is TB3 has more requirements. There’s more to a TB3 connection than a USB-C-based USB one.
As for the connecting cable, all TB3 cables work as USB-C ones, but only high-quality USB-C cables can also work for TB3 — “low quality” ones might work but at a much slower speed or are just unreliable.
For this reason, a TB3 cable tends to come with the TB3 symbol, and that’s the only way one can visually distinguish one from a USB-C counterpart.
And then we still have to deal with other non-USB-C port types, too.
Legacy USB port types
Since there are billions of existing USB devices on the market, it’s essential to support them. And as a result, for the foreseeable future, chances are you’ll run into older USB port types.
In this case, remember that, now, the connecting cable has two different ends: A and B.
The end that goes into a host is called a USB Type-A connector.
Before USB-C, this connector and the corresponding port tye — the USB-A female port — remain the same in all USB standards.
There are two USB Type-A versions:
- USB Type-A: Used in USB 1.1 to USB 2.0 and supports speeds up to 480 Mbps.
- USB Type-A SuperSpeed: Used in USB 3.x standards — more on this below — and supports speeds up to 10Gbps. It tends to come in blue.
Again, these two types use the same port and work interchangeably (at their speed). In other words, USB Type-A SuperSpeed is backward-compatible with USB Type-A.
If you start getting confused, well, it’ll get much worse.
This type is the other end of the cable that goes into a device. This is where things get very complicated.
There are so many variations of standard USB Type-B. That’s not to mention the countless non-standard proprietary Type-B designs, of which the most famous is the Apple Lighting connector that goes into an iPhone.
Each variant of Type-B connectors requires a corresponding port of its own. Physically, one variant’s connector won’t fit into another’s port. As a result, each port type requires a distinctive cable.
So, for example, if you have an iPhone and another non-Apple device, you’ll have to carry at least two cables.
Following are some, out of many, Type-B standards:
- Standard-B (or Type-B): Used in USB 1.1 and USB 2.0 standards. It suits mostly large devices, like printers or scanners.
- Standard-B SuperSpeed: Available only to USB 3.x devices, this port type also works best for large devices, like a desktop external drive.
- Mini-USB (or Mini-B): Significantly smaller than Type-B, this standard is for old portable devices, such as clamshell phone, first-gen portable drives. It’s mostly obsolete now.
- Micro-USB (or Micro-B): Slightly smaller than Mini-USB, this port was once the go-to type for older generations of smartphones and tablets. It’s also being phased out.
- Micro-USB SuperSpeed: The thin version of the Standard-B SuperSpeed. It’s popular in portable hard drives, like the WD My Passport.
Again, as you can imagine, with so many port types, finding the correct cable for your device can be a pain in the rear, especially when you’re in a hurry. This problem is why the USB-C port type mentioned above is such a knight in shining armor.
Legacy Thunderbolt port type
Even though much younger and more “modern,” compared to USB, Thunderbolt has port issues, too.
That’s because, before Thunderbolt 3, there were Thunderbolt and Thunderbolt 2, which use the Mini-Display port type. This standard was one made exclusively for MAC with limited usage.
As a result, there aren’t many “legacy” Thunderbolt devices, and Thunderbolt 3, which is the first revision of the standard available outside of the Apple ecosystem, generally doesn’t support Thunderbolt 2 and Thunderbolt devices. Some can work via an adapter, but in most cases, they don’t work well.
That said, Thunderbolt 3 is the first TB revision that breaks away from the TB norm, which is the only reason why it can compete with USB.
And the fact it uses the USB-C port type means USB is too important to ignore. Future Thunderbolt revisions will also use the USB-C port type.
Final thoughts on USB-C connection type
Small, cute, and well designed, USB Type-C is a new port type aiming to replace all other USB port types, giving users one unifying port standard.
The fact Thunderbolt 3 also uses this port means, from now on, it will be the prominent type. So far, it’s the only USB port that can work all existing USB standards (except for the ancient USB 1.x), and chances are it will also support future connection standards.
By the way, all USB-C devices can connect to a USB Type-A port via an adapter or a Type-A to Type-C cable. So going USB-C allows you to get the best of both worlds, the out-of-the-box convenience with modern equipment and the compatibility with legacy devices when need be.
2. Connection standard: How fast things connect
The connection standard determines how fast a connection is and what you can do with it.
For example, the USB 2.0 standard, determined by the USB Implementers Forum, allows for a connection speed of up to 480 Mbps, and you can also use it to charge a connected device.
We have two primary connection standards, USB and Thunderbolt.
Extra: Connection standard vs connection type
It’s important to note that the connection standard is independent of the connection type mentioned above.
For example, the USB4 is a protocol specification that defines the performance capabilities that can be implemented in a product. (In a way, it’s like a type of engine, like V6 or V8.)
That said, USB4 does not necessarily mean SuperSpeed USB, USB Type-C, USB Standard-A, Micro-USB, or any other USB cable or connector — these are attributes of a particular product. (This is like you can use the same engine in different types of vehicles, like cars vs. trucks.)
Due to multiple name changes of the third USB generation, USB standards can be confusing. Currently, there are the following:
- USB4: This is the latest USB standard that was once referred to as USB 4.0. This is the first USB that has built-in display protocals and, therefore, encompasses Thunderbolt 3. On top of that, it has the best naming convention. USB4 is avaiable in two variants.
- USB4 20Gbps: 20Gbps a speed cap.
- USB4 40Gbps: 40Gbps speed cap.
- USB 3.2 with three variants:
- Gen 2×2: Formerly USB 3.2, and is another upcoming USB standard despite the availability of USB4 — as of 2021, still very few devices on the market have it yet. Cap speed: 20Gbps.
- Gen 2: Formerly USB 3.1 Gen 2, also called USB 3.1 at one point. By 2021, this is a mainstream in 2021. Cap speed: 10Gbps.
- Gen 1: Formerly USB 3.1 Gen 1, also widely called USB 3.0. By 2021 this is the most popular USB standard with almost all existing devices supporting it. Cap speed: 5Gbps.
- USB 2.0: Older standard that’s still quite popular. Cap speed: 480 Mbps.
- USB 1.1: An ancient standard that’s obsolete. Cap speed: 12 Mbps.
To recap, so far, we’ve had USB 1.1 (obsolete), then USB 2.0 (fading away), then USB 3.2 (mainstream), then USB4 (latest) — forget about 3.0 or 3.1, and you’ll be less confused.
Now, keep in mind that USB 3.2 doesn’t exist just by itself but in one of three variations, including Gen 1, Gen 2, and Gen 2×2. (Gen = Generation.)
Generally, USB can also deliver power to a connected device. For this reason, most, if not all, portable drives don’t require a separate power adapter; they draw juice from the host. Via special software or driver, USB can also deliver sound and video signals but only at certain quality levels.
Note on USB cables and speeds
Note that the speeds mentioned above are theoretical. USB has crazy overheads, and the real-world sustained rates depend on the application.
That’s partly because the USB cable has relatively loose requirements and works as a dead wire.
Different manufacturers can make them however they see fit to serve their own products or so that they can sell them for cheap. As a result, most USB cables are considered “low-quality.”
Here’s a quick tip: Don’t expect a cheap generic USB cable to work well with all supported USB devices. It’s best to use the cable that accompanies the particular device.
Most importantly, in any case, you should expect the performance of a USB connection to be between half and 2 thirds of the standard numbers above.
USB vs. Thunderbolt: A brief history
You’ll note right away that the naming of USB 3.2 is a big mess. It’s a good thing that the USB Implementers Forum finally got its act together with USB4.
|Official Name||Year Released||Former Name||Port Type|
|USB 1.1||1998||none||Type-A||Type-B||None||12 Mbps|
|USB 2.0||2000||none||Type-A||Type-B, USB-C||USB 1.1||480 Mbps|
|USB 3.2 |
|2008||USB 3.0 or |
USB 3.1 Gen 1
|Type-A, USB-C||Type-B, USB-C||USB 2.0, USB 1.1||5 Gbps|
|Thunderbolt||2011||None||Mini DisplayPort||Mini DisplayPort||None||10 Gbps|
|USB 3.2 |
|2013||USB 3.1 or |
USB 3.1 Gen 2
|Type-A, USB-C||Type-B, USB-C||USB 3.2 Gen 1 |
USB 2.0, USB 1.1
|Thunderbolt 2||2013||None||Mini DisplayPort||Mini DisplayPort||Thunderbolt||20 Gbps|
|Thunderbolt 3||2015||None||USB-C||USB-C||USB-C devices||40 Gbps|
|USB 3.2 |
|2019||USB 3.2||USB-C||USB-C||USB 3.2 Gen 1/2|
USB 2.0, USB 1.1
|USB4 20Gbps||2019||USB 4.0||USB-C||USB-C||Thunderbolt 3|
|USB4 40Gbps||2019||USB 4.0||USB-C||USB-C||Thunderbolt 3 |
|Thunderbolt 4||Late 2020||None||USB-C||USB-C||Thunderbolt 3 |
|Thunderbolt 5||TBD||None||USB-C||USB-C||Thunderbolt 3|
Relatively young, Thunderbolt has been through three main revisions. Thunderbolt 4 was first announced in July 2020, but you won’t see it on any devices until late 2021 or even 2022.
That said, here is the state of Thunderbolt:
- Original Thunderbolt: This standard uses the Mini DisplayPort port type and has the cap speed of 10Gbps.
- Thunderbolt 2: It also uses Mini DisplayPort and has the cap speed of 20Gbps.
- Thunderbolt 3: Uses USB-C port type. Cap speed: 40 Gbps.
- Thunderbolt x: Going forward newer revesion (TB4, TB5, etc.) will aso use USB-C port type but eith higher speed and likely more feature.
Thunderbolt can do a lot more than USB. It can deliver ultra Hi-Def video/audio signals with high-speed data signals and works as a high wattage power delivery. You can also daisy-chain up to 7 devices together without signal degradation.
By the way, currently, a Thunderbolt 3 port supports the top speed of USB (20Gbps). Future Thunderbolt generations will continue to use USB-C port type and feature USB within.
Extra: Thunderbolt 3 vs Thunderbolt 4
It’s hard to put the finger on the differences between these two. Thunderbolt 3 can virtually do everything Thunderbolt 4 does — the two share the same ceiling speed of 40Gbps.
What sets the two apart is probably the stricter requirements for the TB4 certification. Specifically, Thunderbolt 3 requires a minimum PCIe bus speed of 16Gbps, while TB4 needs PCIe 32Gbps.
|Commercially Available||Rate per lane|
|1||2003||2 Gbps||250 MB/s||0.5 GB/s||1.0 GB/s||2 GB/s||4.0 GB/s|
|2||2007||4 Gbps||500 MB/s||1 GB/s||2.0 GB/s||4 GB/s||8.0 GB/s|
|3||2010||8 Gbps||984.6 MB/s||1.97 GB/s||3.94 GB/s||7.88 GB/s||15.8 GB/s|
|4||2020||16 Gbps||1969 MB/s||3.94 GB/s||7.88 GB/s||15.75 GB/s||31.5 GB/s|
|5||TBD||32 Gbps||3938 MB/s||7.88 GB/s||15.75 GB/s||31.51 GB/s||63 GB/s|
Note: 1 Gigabyte per second (GB/s) = 1000 Megabyte per second (MB/s) | 1 Gigabit per second (Gbps) = 125 MB/s
On top of that, TB4 also requires Intel VT-D-based direct memory access (DMA) protection and has some other minors improvements.
In shorts, TB4 mostly affects hardware makers who need to follow more stringent guidelines to be certified. TB3, on the other hand, offers more flexibility in hardware requirements (and cost) and might not have the same level of stability.
In other words, at the top, TB3 and TB4 products are the same. However, bottom-tier TB3 products sure are lesser than those of the lowest-end TB4.
From the user’s point of view, the two are pretty much the same.
Note on Thunderbolt cables and speeds
Thunderbolt has much better efficiency than USB. That’s partly because the TB cable itself is a device that requires power — it does more than just being a wire.
You can expect the sustained real-worlds speeds to be close to 90% of the numbers mentioned above. But, again, things depend on the particular application.
With lots of capabilities, the Thunderbolt is a standard initially designed to replace all other wired peripheral connections, including HDMI, DisplayPort, and, maybe, even USB.
But Thunderbolt is expensive — it requires extra hardware — and a bit complicated in licensing for hardware vendors to support.
It’s also worth noting that the way Intel has handled Thunderbolt — adding faster speed and more features — kind of makes it cease to be a “standard” and more of an umbrella “protocol” that wraps around a mess of confusing speeds, grades, and features.
My take is Thunderbolt might become counterintuitive at some point in terms of universal compatibility. It has too much of what people don’t need at the expense of cost and application restrictions.
For this reason, the loose, easy, and dirty USB has been winning and will continue to prevail in a popularity contest.
I guess that Thunderbolt and USB will completely converge at some point, as they have in the case of USB4 and Thunderbolt 3.
But even before then, the USB-C port type has already had enough reasons to reign supreme. And for this reason, from the general users’ perspective, the USB-C port type is all you need to really care about.