USB4 vs. Thunderbolt 4: Similarities and Differences Explained

They both have "four" in the name, so they must be similar, right?

USB4 and Thunderbolt 4 were released within one year of each other, and while there are some similarities between these two computer interfaces, there are just about as many differences.

Together, they mark a dramatic shift in hardware connections from one-use ports to multifunctional interfaces that can be used to achieve pretty much anything.

Let’s go over some of the things these specifications have in common and how to differentiate between them.

The specifications of both communication protocols are listed below side-by-side for easy comparison.

USB4

Thunderbolt 4

Connector

Yes

Yes

Minimum PC Bandwidth

20Gbps

40Gbps

Maximum PC Bandwidth

40Gbps

40Gbps

Minimum Video Output Requirements

One 4K display

Two 4K displays

Minimum Data Transfer Requirements

Required Wake from Sleep

No

Yes

Intel VT-d based DMA Protection

No

Yes

Thunderbolt Networking

No

Yes

Minimum Power Delivery (maximum)

7.5W (240W max)

15W (240W)

Universal 40Gbps cables up to 2 meters in length

No

Yes

USB 4.0, formally referred to as USB4, was released by the USB Implementers Forum on August 29, 2019. USB4 defines the interface architecture and not the connector type, but the Forum mandates the use of the USB-C connector for USB-4 ports and cables.

USB4 is based on the Thunderbolt 3 protocol, which Intel made royalty-free in 2019. As a result, it offers a maximum bandwidth of 40Gbps, and gamers will be pleased to learn that USB4 is finally fast enough to support external GPUs. As with other USB versions, USB4 is backward-compatible with older generations, such as USB 3.2 and USB 2.0.

USB4 supports several alternate modes, including Thunderbolt, DisplayPort, and MHL over Alt Mode but drops the HDMI Alt Mode from USB 3.0. Rather than as an optional feature, USB4 certification for laptops and docks requires that all downstream USB-C ports support DisplayPort 2.0, which makes these ports capable of displaying 8K and 16K video at 60Hz.

It also supports DisplayPort and PCIe tunneling, although the latter is optional. This allows for faster transfer rates when sending mixed data. The minimum power delivery output also goes to 7.5W, up from 4.5W in USB 3.0, but the maximum power delivery remains 240W.

Another thing USB4 does better than its predecessors is that it has logos that are more informative. You are now better to tell how fast your USB4 Type-C cable can transfer data and the maximum power output it supports by checking the spec sheet or the ends.

Thunderbolt 4 was first announced in January 2020 at the Consumer Electronic Show (CES) before it was later released in July 2020. It uses the same USB-C connector as Thunderbolt 3 and USB4, but there are certain key differences between USB-C and Thunderbolt.

However, the improvements made in Thunderbolt 4 from the previous version are not as immediately apparent, unlike USB4. For example, Thunderbolt 4 has the same maximum bandwidth as Thunderbolt 3 at 40Gbps, but it increases data transfer rates via PCIe lanes from 16Gbps to 32Gbps.

Thunderbolt 4 is capable of powering two 4K displays at 60Hz (up from a single 4K display in Thunderbolt 3) or a single 8K display at 60Hz. Thunderbolt 4 requires that laptops and docks include at least one port for charging with a minimum power delivery of 15W.

It also includes a Wake from Sleep feature that allows a connected keyboard or mouse to bring the computer out of sleep mode. It has Direct Memory Access (DMA) protection that helps to safeguard against physical DMA attacks by preventing unauthorized access to memory.

It offers support for docks with up to four Thunderbolt 4 ports, three downstream-facing ports, and one upstream-facing port. Keeping up with its universal connector identity, Thunderbolt 4 is compatible with DisplayPort, PCIe, and USB4 (and other generations). It is also backward-compatible with other versions of Thunderbolt.

You've read about the specs, but what are the specific similarities and differences between the two?

Both protocols use the USB Type-C connector to transfer data and power and connect devices. Other similarities include the same maximum bandwidth, DisplayPort support, and the ability to power devices.

Also, USB4 builds upon the same protocol as Thunderbolt 4.0, which makes both interfaces cross-compatible. This means that devices that support Thunderbolt 4 will also support USB 4, and vice versa. However, Thunderbolt 4 devices will have additional features and capabilities beyond those of USB 4 devices.

As for the differences, Thunderbolt 4 is basically USB4 with extra features. It assures you that you are getting the very best of what USB4 has to offer, doubling the number of 4K displays you can run from a single port, the base bandwidth, and the minimum power rating.

It also has a higher minimum data transfer rate of 32Gbps and supports some other features, such as wake from sleep, DMA protection, and a mandatory charging port.

Although the connectors have the same shape, you can generally tell a USB port apart from a Thunderbolt one by the logo next to the port. USB4 ports will have the USB symbol and either “20” or “40”. Thunderbolt 4 cables will usually have the lightning bolt with a 4 underneath. However, identifying Thunderbolt 4 ports on computers without looking at the spec sheet is not possible.

Thunderbolt cables are also able to work passively, that is, without a built-in electric circuit. This means that normal cables (without boosters) are capable of maintaining the maximum bandwidth of 40Gbps even at up to lengths of two meters, while USB4 is incapable of supporting 40Gbps on cables that are two meters or longer and reduces the data rate to 20Gbps.

Laptops and docks with USB4 will be cheaper than those with Thunderbolt 4 due to the lower minimum requirements. The USB4 protocol is also likely to be more widespread among users for the same reason.

There is no doubt about it. Thunderbolt 4 is superior to USB4, but it may not be the best option for you, depending on your preferences.

If you are looking for an interface that offers the absolute best in power and performance, then look no further than Thunderbolt 4-enabled hubs, docking stations, and laptops. On the other hand, if you are more concerned about price and having a wide selection of accessories to choose from, then USB4 may be the best option for you.

Tomisin is a staff writer at MUO with a penchant for breaking down complex topics into easily digestible bits. He first started writing reviews of phones and gadgets in 2016 and loves reading spec sheets and tinkering with new technology.Currently, he writes about DIY tech for MakeUseOf and looks forward to expanding his horizons.