Thursday, April 22nd, 2021

Device Connections Explained: It’s All about USB-C

If you’re not sure of the difference between USB-C vs. Thunderbolt 3, or between USB 3.0 vs. USB 3.2, you’re not alone. But mind you, that’s a small problem to have. Not so long ago, we had to also deal with a myriad of other peripheral connections types, like 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, connection types and connection standards.

The SanDisk Extreme Pro Portable SSD's USB-C port
SanDisk Extreme Pro Portable SSD

A. Connection type: How things fit

To connect a device (like a portable drive) to a host (like a computer), you need a cable. Like all cables, it 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 hole the cable’s end plugs into is a female port or port 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 cable 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. 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.

The Samsung X5 is a Thunderbolt 3 drive. Note its TB3 cable, which looks the same as a USB-C one.

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, 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 one.

As for the connecting cable, all TB3 cables work as USB-C cables, but only high-quality USB-C cables can also work as TB3 ones — “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.

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.

DS620slilm Back
The USB Type-A port is everywhere. Here are two of them behind this small NAS server.

USB Type-A

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. However, there are two USB Type-A versions:

USB Type A 1
USB Type-A and Type-A SuperSpeed connectors. (Not to scale.)
  • 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.

USB Type-B

This type is the other end of the cable that goes into a device and where things get complicated. There are so many variations of standard USB Type-B. That’s not to mention the countless 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:

USB Type B Standards
A few variations of USB Type-B connectors. (Not to scale.)
  • 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.
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Again, as you can imagine, with so many port types, finding the right cable for your device can be a pain in the rear, especially when you’re in a hurry. This problem is why USB-C is such a knight in shining armor.

USB Type B including USB-C
Clockwise: USB-C, Type-B, Mini-B, Micro-B, Type-B SuperSpeed, Micro-B SuperSpeed.

Legacy Thunderbolt port type

Even though much younger and more “modern,” Thunderbolt has port issues of its own. Before Thunderbolt 3, there were Thunderbolt and Thunderbolt 2, which use the Mini-Display port type.

That plus the fact there aren’t many “legacy” Thunderbolt devices — the connection was once available exclusively to Apple’s ecosystem — Thunderbolt 3 generally doesn’t support Thunderbolt 2 and Thunderbolt devices. Some can work via an adapter, but in most cases, they don’t work well.

Connection type: The takeaway

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, going forward, 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.

B. Connection standards: 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 allows for a connection speed of up to 480 Mbps, and you can also use it to charge a connected device.

Everything would be quite straightforward if the USB Implementers Forum could just make up its mind on a simple issue that is how to call a USB revision. (Hint: Don’t count on it!)

USB standards

Due to multiple name changes of the third USB generation, USB standards can be confusing. Currently, there are the following:

  • USB 3.2 Gen 2×2: Formerly USB 3.2, and is the upcoming USB standard. Cap speed: 20Gbps.
  • USB 3.2 Gen 2: Formerly USB 3.1 Gen 2, also called USB 3.1 at one point. Cap speed: 10Gbps.
  • USB 3.2 Gen 1: Formerly USB 3.1 Gen 1, also widely called USB 3.0. Cap speed: 5Gbps.
  • USB 2.0: Older standard that’s still quite popular. Cap speed: 480 Mbps.
  • USB 1.1: An old standard that’s now obsolete. Cap speed: 12 Mbps.

To recap, so far, we’ve had USB 1.1, then USB 2.0, then USB 3.2 — 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.) There will be USB 4.0 at some point though it could also be called USB 4.x or something else entirely. Who knows!

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.

Important note on USB speeds

Note that the speeds mentioned above are theoretical. USB has crazy overheads and the real-world sustained rates depend on the application. Generally, you should expect between half and 2 thirds of the numbers above.

USB vs. Thunderbolt in brief

Official NameYear ReleasedFormer NamePort Type
 at Host
Port Type
 at Device
USB 1.11998noneType-AType-BNone12 Mbps
USB 2.02000noneType-AType-B, USB-CUSB 1.1480 Mbps
USB 3.2 
Gen 1
2008USB 3.0 or 
USB 3.1 Gen 1
Type-A, USB-CType-B, USB-CUSB 2.0, USB 1.15 Gbps
USB 3.2 
Gen 2
2013USB 3.1 or 
USB 3.1 Gen 2
Type-A, USB-CType-B, USB-CUSB 3.2 Gen 1, 
USB 2.0, USB 1.1
10 Gbps
Thunderbolt 2011NoneMini DisplayPortMini DisplayPortNone10 Gbps
Thunderbolt 22013NoneMini DisplayPortMini DisplayPortThunderbolt 20 Gbps
Thunderbolt 32015NoneUSB-CUSB-CUSB-C devices40 Gbps
USB 3.2 
Gen 2×2
2019USB 3.2USB-CUSB-CUSB 3.2 Gen 1/2, 
USB 2.0, USB 1.1
20 Gbps
Thunderbolt 4Late 2020NoneUSB-CUSB-CThunderbolt 3, 
USB-C devices
40 Gbps
USB 4.0TBDNoneUSB-CUSB-CUSB-C devices40 Gbps
Hardware specifications: USB vs. Thunderbolt

Thunderbolt standards

Relatively young, Thunderbolt has been through three revisions.

  • 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 can do a lot more than USB. Among other things, it can deliver ultra Hi-Def video/audio signals together with high-speed data signals, and also 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 USB 3.2 Gen 2 (10 Gbps) speed. But when USB 3.2 Gen 2×2 (20 Gbps) is available, it likely will also be implemented within Thunderbolt 3. Future Thunderbolt generations will likely continue to use USB-C port type.

Important note on Thunderbolt speeds

Thunderbolt has much better efficiency than USB. 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 3 is a standard initially designed to replace all other wired peripheral connections, including HDMI, DisplayPort, and, maybe, even USB. But it’s expensive and a bit complicated in licensing for hardware vendors to support.

For this reason, USB has been winning and will continue to prevail in a popularity contest. My guess is, at some point, Thunderbolt and USB will converge, as they should. But even before then, the USB-C port type has already had enough reasons to reign supreme.

2 thoughts on “Device Connections Explained: It’s All about USB-C”

  1. I know you know this, but just as a reminder since it wasn’t mentioned in the article: USB4 is coming!! With 10, 20, and 40 gbps speeds. USB4 will be type C only, and some manufacturers may (or may not) include thunderbolt 3 into their USB4 solutions. Also, thunderbolt 3 has seen a tepid adoption in the industry in part because intel was charging a royalty for the technology. But intel has changed its mind and donated thunderbolt 3 to the USB-IF for implementation in USB4.


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