7 key differences between USB4 and USB 3

Every few years, a new USB specification is released that builds on the foundation laid by its predecessors. However, due to the nature of the interface, new versions do not always bring obvious changes compared to the previous version.

So let's take a close look at the latest USB specification, USB4, and the improvements it brings over the older USB 3.

What is the difference between USB4 and USB 3?

USB4, also known as USB 4, is the latest generation of the Universal Serial Bus standard. It was released in August 2019 and is based on the Thunderbolt 3 specification, which Intel made available royalty-free the same year. Thunderbolt 4 and USB4 are quite similar for this reason. It mandates the use of a USB-C connector and offers a number of improvements, including faster data transfer speeds and better product naming.

USB 3 or also known as Super Speed ​​is the third major version of the Universal Serial Bus standard. The first USB 3.0 specification was released in November 2008 and has since been replaced by subsequent specifications USB 3.1 (2013) and USB 3.2 (2017). USB 3 can be quite confusing, so check out our article on the differences between USB-C and USB 3 to get a clear idea of ​​how it all works.

1. Supported connector types

USB4 is the first major USB standard that requires the use of a specific connector to function, in this case the USB Type-C connector. For this reason, you won't get USB4 transfer speeds with anything other than a USB C-to-C cable.

On the other hand, the USB 3.2 specification does not mandate the use of a single connector. Instead, it works with 4 different types of USB connectors: SuperSpeed ​​​Type-A (which has 5 more pins than the USB 2.0 version), SuperSpeed ​​​​​​Type-B connector, USB 3.0 Micro-B and USB- C. Generally this is true, but USB 3.2 Gen 1 x 2 and Gen 2 x 2 require a full-featured USB C-to-C cable to operate across multiple lanes.

2. Transmission speed

As expected, USB4 offers faster data transfer speeds than USB 3. USB 3.2 Gen 2x2, the fastest USB 3 variant, reaches a maximum speed of 20 Gbps, which is the minimum speed that USB4 offers. USB4 can transfer data at speeds up to 120Gbps like USB4 2.0.

USB4 also introduces data tunneling, allowing multiple display and data protocols to share available bus bandwidth efficiently. This can deliver faster transfer speeds when sending mixed data, even with the same throughput as USB 3.2.

3. Power Delivery

Charge your phone from your laptop's USB PD port

The first Power Delivery specification, USB PD 1.0, can deliver up to 100W using 6 fixed power configurations. Power Delivery 2.0 introduced more flexible rules, and USB PD 3.1 increased the maximum amount of power that can be delivered over a USB cable to 240W.

Both USB4 and USB 3 support power delivery up to 240W because Power Delivery is a feature of the USB-C connector and not the protocol. All you need is a high-quality, full-featured USB C-to-C cable to use USB PD to its full potential.

The main difference between USB 3 and USB4 PD is that the minimum power supply increases from 3.0W to 7.5W in USB4, but the maximum power supply remains the same at 240W.

4. Backwards compatibility

Backwards compatibility is important to the USB standard (rightfully so), and newer versions are designed to work with older ones. This does not necessarily mean physical compatibility as certain USB connectors are designed to connect to specific USB ports and will not connect to others.

Rather, it means that USB devices will always be able to communicate with other devices once they are physically connected, regardless of generation.

Therefore, USB 3 and USB 4 are backward compatible with previous specifications. USB4 adds Thunderbolt 3 compatibility, although this is primarily an optional feature.

5. Naming conventions

Besides the official product name, USB specifications always have a customer-facing marketing name. USB 1.0 was called Full Speed, USB 2.0 was named High Speed ​​and USB 3.0 was introduced as SuperSpeed, this label became quite confusing and was eventually dropped when USB4 was introduced.

USB ports and cables are now identified with a naming scheme that uses the syntax "USB XGbps", where X is the transfer rate in Gb/s. Power may also be included next to transmission speed to indicate the Power Delivery rating.

6. Required and recommended features

USB4 introduces a set of minimum standards that manufacturers must meet to label their products as USB4. First, it mandates the use of a Type-C connector. It also claims DisplayPort Alternate Mode support, dual-lane operation, and Thunderbolt 3.

In contrast, USB3 has no mandatory features except those that are specific to the connector or required for a particular mode of operation.

7. Price vs performance

The enhanced features and relative novelty of USB4 mean that the cables and devices that deliver it will be more expensive than USB 3. However, as USB4 becomes more popular and manufacturing costs decrease, USB4 may will become more and more affordable. However, USB4 offers many of the same features as Thunderbolt 4 while being much cheaper. So it's all pretty relative.

USB 3 is a budget-friendly choice, delivering high performance at a cheaper price. USB 3 will appeal to users looking for a cost-effective solution to basic connectivity needs. On the other hand, USB4 will be more valuable to gamers, video editors, and other power users. It will also come in handy when you want to switch computers and need to move a lot of files.

Is USB4 or USB 3 best for you?

While it's no surprise that the newer standard outperforms the previous one, what's impressive is that USB4 offers a clear improvement over USB3, especially compared to Thunderbolt 3 and 4.

In most cases, you won't regret either option. It's up to you to decide whether USB4's outstanding new features are worth the additional price.

Marvin Fry

Update 29 September 2023