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.

thunderbolt 4

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 4Thunderbolt 3USB4USB 3/DP
1 universal port
40Gb/s cables up to 2 meters
Accessories with up to 4 TB ports
Min PC speed requirement40Gb/s40Gb/s20Gb/s
(40Gb/s is optional)
10Gb/s
Min PC video requirement2 x 4K displays
or
1 x 8K display
1 x 4K display1 display (no min resolution)1 display (no min resolution)
Mini PC data requirementsPCIe 32Gb/s
USB 3.2 10Gb/s
PCIe 16Gb/s
USB 3.2 10Gb/s
USB 3.2 10Gb/sUSB 3.2 5Gb/s
PC charging port requiredAt least one
PC wake from sleep w/TB dock connectedRequired
Min PC port power for accessories15W15W7.5W4.5W
Thunderbolt networking
Mandatory certification for PCs and accessories
Intel VT-d based DMA protection required
USB4 specificationCompliantCompatibleCompliantCompatible

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.

Some of the first and highest profile computers to feature USB4 ports with Thunderbolt 3 technology are Apple’s 2020 MacBook Pro 13, MacBook Air, and Mac Mini featuring Apple M1 processors.

Mac Mini (2020)

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.

via Intel, Thunderbolt, and USB-IF

This article was originally published July 8, 2020 and last updated September 10, 2020. 

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  1. The author/editor of this article needs to realize there is a difference between GB/s and Gb/s. In many places throughout the article is states speeds using GB/s when in fact it is Gb/s. To be clear every reference to speed in this article should in fact be in Gb/s.

  2. I’m waiting to see some research and maybe a white paper about Wireless interference from the USB4/TB4 data transmissions.

    After USB 3.0 came out, Intel found that USB 3.0 data transmissions created a high amount of radio interference that affected a frequency range that included 2.4ghz, so it would interfere with 2.4ghz Wifi, and Bluetooth.

    While most people have moved further away from 2.4ghz wifi since the launch of USB 3.0, I’m still hoping to see some data about this. I hope they’re ahead of the game this time. If it interferes with 5ghz this time, we’re screwed.

  3. So still the same TDP limit for laptops and still the huge bottleneck for any eGPU to be useful for gaming.

  4. Isn’t the speed measured in Gbps not GB/s for these standards?

    40Gigabits per second is a lot less than 40Gigabytes per second.

    also, existing thunderbolt 3 ports were mostly limited to 20Gbps variants in many devices, only supplied two pcie lanes instead of the full four.

  5. thanks, that’s really interesting. From an AMD perspective, will USB4 be suitable for eGPU enclosures, which have used Thunderbolt. It’s what has kept me on my Hades Canyon NUC instead of switching to something with a 4000U set up…

    1. Short answer: No.

      Long answer:
      (I think it’s a bit of a mess, so I’ll try to clear up some of it.)

      Most USB’s are regular USB 3.0, and it’s a 50/50 split between Type-A and Type-C connection.
      The very cheap stuff, even expensive Chinese Phones, still use the outdated USB 2.0 protocol.
      When showcased and released, TB3, made a lot of high promises.
      In general, TB3 failed to live up to it, because it was expensive to license and the external controller was also a cost most ODMs didn’t want to bare. Apple is the exception.
      The minimum specs for TB3 were quite low compared to its maximum specs, and many TB3 Laptops opted for the minimum specs. Despite this, it is still much faster than USB 3.0 and 3.1 and 3.1.2 protocols.
      So most TB3 Laptops weren’t a good connection for eGPUs. The more premium eGPU and Laptop combinations were more acceptable, but they had their limits (ie/ GTX 1080 eGPU, reduced to performance of GTX 1070).
      USB 4 is an updated model of TB3, so in a sense it is superior.
      However, the minimum requirements are actually lower, and the certification to get USB 4 is actually more lenient than TB3. So what we can expect is USB4 is going to be worse than TB3 in the real world.
      TB4 tries to make a few improvements over TB3, and I believe, vendors will stick with USB 4 for the most part. Any vendor who opts for TB4 is “wasting money” so they will get the full-specced TB4 connection.
      Overall, this will bring a slight improvement to the eGPU table. So if we conclude TB3 wasn’t too capable for eGPUs, we can safely conclude the same for TB4 unfortunately.
      The bigger impact should come from AMD Ryzen 4000 or Ryzen 6000 Laptops, as it will reduce some of the CPU bottlenecking in Video Games.

  6. To be clear, DMA is direct memory access, not attack, but what they are trying to prevent are direct memory access attacks (DMA attacks).

      1. One more quickie for you.
        “And Intel says the minimum video and data transfer speed requirements four Thunderbolt 4 are double those for Thunderbolt 3.”

        “requirements four Thunderbolt” should be “for”

        1. The minimum requirement for Thunderbolt 4 is 32Gb/s where Thunderbolt 3 minimum requirement was 16 Gb/s

  7. Nowadays, I only use cables/adapters for connecting to a monitor, power and the occasional USB drive. USB 3.0 with Type-C connections, PD and DisplayPort has been more than good enough for my consumer needs.

    It’s similar at work too since my work mostly involves logging into remote high performance compute servers where my local PC/notebook is just a terminal.

    The only time I ever used a Thunderbolt port (the non-type-C port) was for an older MacBook Pro needing to connect to an older Apple monitor.

    1. Not sure what that has to do with my question. FWIW I use a Thunderbolt 3 dock (CalDigit TS3 Plus) and a Thunderbolt monitor (LG UltraFine 5K). The dock enables me to use a single connection on my MacBook Pro for power, display, and an assortment of other accessories.

      1. “Not sure what that has to do with my question.”

        More than likely nothing. The comments are just a bit oddly arranged. I’ve noticed it earlier.

      2. Not sure what that has to do with my question.

        It has nothing to do with your comment because I didn’t reply to you. Just as “next” said, the comment format/display and general reply issues has been happening for the last while due to the ongoing changes to this site.

        Anyway, I still don’t have anything to say about your topic.

        1. Sorry about that — looks like the reply box moves to the bottom of the page now, where it’s harder to see after a few people have left comments, making the reply button seem like the obvious choice. I’ll see if I can do something about that.

        2. Well, that was easier than I thought — just had to flip things so that the most recent comments are on top rather than the bottom, which probably makes more sense anyway.

    1. Thunderbolt is an Apple developed technology. On Intel boards, if there is such a thing, future macs will likely support Thunderbolt 4.

      On Apple Silicon? I think its still likely. Apple likes Thunderbolt. Id guess 80% chance Apple Silicon will support TB4.

    2. Looks like Apple answered your question: https://www.theverge.com/circuitbreaker/2020/7/8/21317980/apple-silicon-intel-thunderbolt-arm-macs-support-usb-c

      “Over a decade ago, Apple partnered with Intel to design and develop Thunderbolt, and today our customers enjoy the speed and flexibility it brings to every Mac. We remain committed to the future of Thunderbolt and will support it in Macs with Apple silicon,” commented an Apple spokesperson, in a statement to The Verge