Thunderbolt 4 and USB4 are next-gen technologies that are similar in a lot of ways. But there are also some key differences.
Both use the same USB-C connector. Both are capable of data transfer speeds up to 40GB/s. Both can deliver enough power to charge a laptop, and both can drive an external display.
But Thunderbolt 4 is guaranteed to meet certain minimum specs that USB4 devices may not always match.
With the first devices with USB4 and/or Thunderbolt 4 now shipping, let’s take a look at what sets the two apart from one another… and their predecessors.
If you just want an at-a-glance way to see how the standards stack up against one another, scroll down and check out our comparison table. But it’s also helpful to understand a little of the history of USB and Thunderbolt.
USB technology has been around for 24 years at this point, and the fourth major update to the USB specification is set to launch this year. It incorporates Thunderbolt 3 technology which means that some USB4 products may be capable of all the features available via Thunderbolt 3 including the ability to use a single cable to power your PC, carry video output to a display, and transfer data.
It’s a major step up from USB 3 and earlier technology. But device and accessory makers have some flexibility in how they use USB4. For example, the USB4 specification supports theoretical speeds up to 40Gb/s, but some PCs, phones, or tablets with USB4 ports may only be able to handle speeds up to 20Gb/s. The same goes for USB4 cables and docking accessories.
Unlike earlier versions of USB technology, USB4 will have a single standard connector. Say goodbye USB-A, micro USB, and all the others. If a device has a USB4 port, it will be a USB-C port.
Unfortunately USB-C just describes the connection type. Up until now, glancing at a USB-C port wasn’t necessarily enough to tell you if you were looking at a USB 2.0 or USB 3.x device. If there’s a little lightning logo near the port, at least you could tell it was a Thunderbolt 3 port.
Hopefully by the time USB4 products start to ship, we’ll see clear labeling that follows the USB logo usage guidelines so you can tell if you’re looking at a 20Gbps or 40Gbps port.
Thunderbolt is a brand name for technology developed by Intel and Apple. It first debuted in 2011, and version 4 is set to launch in the second half of 2020. And in order to use the Thunderbolt 4 brand, device and accessory makers will need to pay Intel a license fee… and receive certification from Intel that guarantees their products meet the minimum requirements for Thunderbolt 4.
While Thunderbolt 3 started out with similar restrictions, Intel eventually contributed the protocol to the USB Promoter group, which is why USB4 will have many of the features previously only available via Thunderbolt 3.
Thunderbolt 4 won’t be any faster than Thunderbolt 3, with both topping out at speeds of 40Gb/s. But the new version will bring some new features designed to bring better security and support for more usage scenarios.
Intel has also announced that in order to receive Thunderbolt 4 certification, devices will need to meet a minimum set of requirements that will set them apart from other standards.
For example, any PC with Thunderbolt 4 technology will have to have at least one TB4 port that you can use to charge the computer. Thunderbolt 4 docking stations will need to support wake-from sleep when you touch the mouse or keyboard of a connected computer. Protection from direct memory access (DMA) attacks is also required. And Intel says the minimum video and data transfer speed requirements for Thunderbolt 4 are double those for Thunderbolt 3.
Here’s an overview of some of the differences between Thunderbolt 4, Thunderbolt 3, USB4, and USB 3 (with DisplayPort technology):
|Thunderbolt 4||Thunderbolt 3||USB4||USB 3/DP|
|1 universal port||✓||✓|
|40Gb/s cables up to 2 meters||✓|
|Accessories with up to 4 TB ports||✓|
|Min PC speed requirement||40Gb/s||40Gb/s||20Gb/s|
(40Gb/s is optional)
|Min PC video requirement||2 x 4K displays|
1 x 8K display
|1 x 4K display||1 display (no min resolution)||1 display (no min resolution)|
|Mini PC data requirements||PCIe 32Gb/s|
USB 3.2 10Gb/s
USB 3.2 10Gb/s
|USB 3.2 10Gb/s||USB 3.2 5Gb/s|
|PC charging port required||At least one|
|PC wake from sleep w/TB dock connected||Required|
|Min PC port power for accessories||15W||15W||7.5W||4.5W|
|Mandatory certification for PCs and accessories||✓||✓|
|Intel VT-d based DMA protection required||✓|
Intel notes that the new Thunderbolt 4 standard also enables support for docking stations with up to four TB4 ports and Thunderbolt 4 cables up to 2 meters (about 6.6 feet) in length with support for data transfer speeds of 40Gb/s.
Some of the first computes to feature Thunderbolt 4 technology are laptops featuring 11th-gen Intel Core “Tiger Lake” processors, since the chips feature an integrated Thunderbolt 4 controller. Theoretically we could see PCs with AMD chips and Thunderbolt 4 ports, but this is likely to be less common since Thunderbolt technology isn’t bake into any AMD chipsets so far.
While that doesn’t mean every laptop or other PC with a Tiger Lake chip will support Thunderbolt 4, odds are that if you buy a new computer with an older Intel processor (or an AMD or ARM chip), it won’t support Thunderbolt 4… although that doesn’t necessarily mean you won’t eventually be able to get a device with a different chip that also supports the technology. Intel plans to release a set of Intel 8000 series Thunderbolt 4 controllers later this year.
Obviously Intel is playing up the benefits of Thunderbolt 4 not being an open standard. The certification and testing process means you know what you’re getting when you buy a device labeled with the Thunderbolt 4 logo.
But theoretically there’s nothing stopping USB4 device and accessory makers from incorporating most of the same technologies. And they can save a bit of money on licensing and testing fees if they do that.
Still, there’s no guarantee that a USB4 product will support top speeds exceeding 20Gb/s or that it will support multiple high-resolution displays or USB power delivery capable of charging a laptop. So the easiest way to know if a device will support those features at a glance is to check for the Thunderbolt 4 logo.
Oh, there’s one more interesting thing to note about Thunderbolt 4. Intel may be the driving force behind the technology at this point, but it was initially developed in partnership with Apple. So what happens when Apple starts releasing Mac computers with Apple Silicon rather than Intel chips?
According to Apple, those computers will continue to support Thunderbolt technology.
This article was originally published July 8, 2020 and last updated September 10, 2020.