USB4 vs. Thunderbolt 4: What’s the difference?

Thunderbolt 4 and USB4 are becoming the standard for connectivity in computers. Both
use the USB Type-C connector and can run at speeds as high as 40Gbps. Additionally, they support
video and power passthrough.
While these technologies share many similarities, it can be challenging to tell them apart. When you
go beyond the appearance, you’ll find there are significant differences between Thunderbolt
4 and USB4.

To make it easier to understand, here’s a detailed comparison to help clarify the distinctions
between these connection types.
Devices featuring either Thunderbolt 4 or USB4 ports will still serve you in the best way
according to today’s standards, but knowing the differences will help you to make a more informed
decision when looking for your next purchase.

What is Thunderbolt 4?     

Thunderbolt 4 is an advanced, high-performance port that is the latest evolution in connectivity technology.

It’s been specifically made to enhance data transfer, video, and power delivery capabilities, providing an efficient solution for contemporary computing and peripheral connectivity requirements.

The highlight feature of Thunderbolt 4 is a minimum bandwidth requirement of 32 Gbit/s for PCIe links, allowing accelerated data transmission and optimizing (and usually increasing) performance and reducing completion times for a wide range of tasks.

I want to draw attention to Thunderbolt’s support of dual 4K displays (DisplayPort 1.4) at minimum, which lets multi-monitor setups have higher bit rates for each display, directly translating to better image quality across almost all display configurations. 

One of its even better upgrades is the integration of Intel VT-d-based Direct Memory Access protection, which effectively mitigates the risks of a physical DMA attack, safeguarding sensitive data and maintaining system integrity in case your device is ever compromised.

Furthermore, Thunderbolt 4 introduces support for Thunderbolt Alternate Mode USB hubs (“Multi-port Accessory Architecture”), expanding connectivity options beyond traditional daisy-chaining. 

This extended compatibility ensures seamless integration with both Thunderbolt 4 and Thunderbolt 3 devices, offering much smoother experiences for users that rock previous-gen hardware.
Thunderbolt 4 retains the speed of Thunderbolt 3, still clocking a maximum bandwidth of 40 Gbit/s. That is probably the only similarity aside from the use of similar ports. Below is a table highlighting major generational differences from Thunderbolt 3 to 4:

	Thunderbolt™ 4	Thunderbolt™ 3
Connector type	USB-C	USB-C
Total bandwidth	40 Gbps	40 Gbps
Minimum bandwidth available for data transfer	32 Gbps	16 Gbps
Display	Up to two 4K monitors or one 8K monitor	One 4K monitor
Thunderbolt™ ports per accessory	Up to four ports	Up to two ports
Laptop charging	Up to 100W on at least one computer port	Supported, but not required
System wake from sleep from connected accessory	Required	Supported, but not required
Intel® VT-d-based direct memory access (DMA) protection	Required	Supported, but not required
USB4 specification	Compliant	Compatible

What is USB4?

SB4 is a technical specification officially released by the USB Implementers Forum (USB-IF) on August 29, 2019. This specification is built upon the foundation of the ThunderboltTM 3 protocol specification, generously contributed to the USB-IF by Intel. USB4 aligns closely with the Thunderbolt 4 specification to ensure compatibility and efficient operation.

One of the notable features of the USB4 architecture is its dynamic capability to share a single high-speed link among multiple hardware endpoints, optimizing data transfer for various data types and applications.

In contrast to previous USB protocol standards, USB4 mandates the exclusive use of the Type-C connector and USB Power Delivery (USB-PD) specification. The standard ensures that USB4 products must support a minimum throughput of 20 Gbit/s, with the option to achieve a higher throughput of 40 Gbit/s when needed.

Interoperability with Thunderbolt 3 products is optional for USB4 hosts and peripheral devices. However, USB4 hubs are required to support interoperability with Thunderbolt 3 on all of their downstream-facing ports, and USB4-based docks must offer this compatibility on their upstream-facing port as well as all their downstream-facing ports.

On October 18, 2022, the USB Implementers Forum updated the USB4 specification and introduced new capabilities: including an 80 Gbit/s bi-directional mode and a 120 Gbit/s asymmetric mode, which enhanced the overall versatility of USB4 technology.

The transfer modes supported by USB 4 endpoints are listed below:

Mode	Host	Hub	Peripheral device
USB4 Gen 2 (10 or 20 Gbit/s)	Yes	Yes	Yes
USB4 Gen 3 (20 or 40 Gbit/s)	Optional	Yes	Optional
USB4 Gen 4 (80 or 120 Gbit/s)	Optional	Optional	Optional

Note that USB 10Gbps and USB 5Gbps reflect older USB standards, and USB4 is reflected by the new USB 20Gbps and USB 40Gbps.

Similar differences can be observed when looking at the updated cable logos. From now on, certified cables must display both the maximum wattage and data transfer speeds, except for those using the older Hi-Speed standard.

It is essential to know that the use of brand names for USB devices is not compulsory, and such branding is specifically reserved for USB devices that have undergone certification by the USB Implementers Forum (USB-IF). However, it is crucial to recognize that the scope of certified USB devices represents only a fraction of the vast and diverse range of USB products available in the market.

One significant factor contributing to this disparity lies in the fundamental nature of the USB standard itself. Unlike proprietary technologies like Thunderbolt 4, which require manufacturers to obtain licensing directly from Intel, USB is an open standard. This openness allows anyone to freely utilize the USB technology without any licensing constraints, contributing to its widespread adoption and ubiquity in the tech industry.

Nevertheless, the open nature of the USB standard also presents certain challenges. As the USB-IF is the governing body responsible for overseeing and ensuring adherence to the USB specifications, they may face limitations in effectively regulating the entire landscape of USB products. Since manufacturers are not bound by strict licensing agreements, there is a possibility of some companies creating USB devices that do not fully comply with the official USB specifications.

Consequently, some USB devices may be labeled inaccurately or ambiguously. For instance, a manufacturer might brand their device as “USB4 Version 2” without adhering to the complete USB4 standard or not provide any branding at all, making it difficult for consumers to ascertain the exact capabilities and features of the product.

Having been acquainted with the distinct characteristics of both of these connectivity standards, let us now delve into a direct comparison.

Comparing USB4 and Thunderbolt 4 Side by Side:

To draw an easy comparison between both of these technologies, take a look at the below table that distinguishes both in terms of their most important features:

Feature	Thunderbolt 4	USB4
Maximum Speed	Up to 40Gbps	Up to 40Gbps
Minimum Link Speed	32Gbps	20Gbps
Minimum Video Support	Two 4K displays	One 4K display
Licensing Costs	Higher	Lower
Data Transfer Protocol	Thunderbolt protocol	USB4 protocol
Power Delivery	Up to 100W	Up to 100W
Minimum PC port power for accessories	15W	7.5W
Compatibility with Older Devices	Yes, with adapters	Yes, with adapters
Universal 40Gbps cables	Yes	No
Accessories with four Thunderbolt ports	Yes	No
Required PC charging on at least one computer port	Yes	No
Required PC wake from sleep	Yes	No
Thunderbolt networking	Yes	No
Mandatory certification	Yes	No
Cable testing and cable quality audits	Yes	No
Required Intel VT-d based DMA protection	Yes	No
Daisy Chaining Support	Yes	No
Required Cable Type	Thunderbolt or USB-C	USB-C

In easy terms, yes, Thunderbolt is hands down the better option. If direct spec-by-spec comparisons of both of these technologies are looked over, USB4 seems nonsensical to have been in existence, but take a look at real-world examples where each of these two will have an advantage over one another:

Where Thunderbolt 4 is favored over USB4:

• Professionals, content creators, and power users who demand top-tier performance and rely on seamless multi-display setups, high-speed data transfer, and data-intensive tasks as part of their workflow.

• Users who need to connect multiple Thunderbolt devices to a single PC benefit from Thunderbolt 4’s efficient handling of multiple peripheral connections.

• Users who prioritize Direct Memory Access (DMA) protection to physically safeguard against DMA attacks, a feature offered by Thunderbolt 4. Although this may not be of much importance to the average user, it still is an important security feature to have.

Where USB4 is preferred over Thunderbolt 4:

1. Manufacturers and device developers seeking a cost-effective solution with lower licensing expenses, making USB4 an appealing choice.

• Users who do not require the advanced features and performance capabilities of Thunderbolt 4 and are looking for a more budget-friendly option.

• Device makers which desire the freedom to customize their implementations based on specific requirements without being encumbered by licensing fees, a level of flexibility offered by USB4.

So, Which One’s ‘The Right One’?

Having gone over the differences, it’s pretty apparent that Thunderbolt is the more ‘elite’ standard compared to USB 4. But not all circumstances require such high-grade tech, and in cases like this USB takes the lead with its ultimate power: Lesser money. An informed and concrete decision can be taken by keeping the following three points in mind: –

Cost Efficiency: USB4 is much more cost-effective due to its lower licensing expenses, making it an attractive option for various devices. The reduced licensing cost is definitely a significant financial advantage for manufacturers and device developers, allowing for more efficient budget allocation while delivering high-performance connectivity solutions.

In contrast, Thunderbolt 4 may involve relatively higher licensing costs, which could impact the overall affordability of devices incorporating this technology. Manufacturers should carefully weigh the value proposition offered by Thunderbolt 4 against the associated licensing expenses.

Enhanced Flexibility: USB4’s advantage lies in its enhanced flexibility and openness, affording device makers the freedom to tailor their implementations without being constrained by licensing fees.

On the other hand, while delivering robust performance and an extensive set of features, Thunderbolt 4 might impose certain limitations on customization in the future due to potential licensing constraints, although it is highly speculative at this moment. Device manufacturers must carefully consider the balance between Thunderbolt 4’s superior performance capabilities and the extent to which design freedom may be compromised.

Lower Minimum Performance Thresholds: One consideration with USB4 is that it features a lower minimum link speed of 20Gbps. While this speed is still all that an average user will need, it may potentially impact the baseline performance of USB4 devices in certain high-demand applications that require more bandwidth.

In contrast, Thunderbolt 4 sits a tier above with its guaranteed minimum performance level, which guarantees the capability to support a minimum of two 4K displays and data transfer speeds of up to 32Gbps. This higher baseline performance can be a decisive advantage for users seeking seamless multi-display setups, high-speed data transfer, and other data-intensive tasks.

Closing Words

By this point, you have a pretty clear understanding of these technologies and their differences. Both Thunderbolt4 and USB4 are bleeding edge and great in their own rights. But if you had to choose one, going over your use cases might help as Thunderbolt4 may not offer the best value if there’s a tight cap on budget.

Ultimately, getting either of these is a no-brainer in today’s fast-paced world. As an average user, there will be no harm in going for USB4, and any substantial differences won’t be noticeable if you instead choose the other option, but if needs demand the high bandwidth and other highlights of Thunderbolt4, and if, of course, the budget allows it, then definitely Thunderbolt 4 (which is also now royalty-free) is the right choice for users.