USB 3.1 has a Gen 1 and Gen 2 subdivision. These are further divided into generations. USB 2.0 received a single revision, but USB 3 has had the most revision work with USB 3.1 and 3.2. USB 1.1 is actually the most widely-adopted USB 1 standard, with virtually no USB 1.0 devices making it into the hands of users. USB 3 is the most recent standard at the time of writing and has a theoretical speed of an astonishing 5 Gbps (gigabits per second).The marketing name for USB 2 is “High Speed”. USB 2 is way faster, with a maximum theoretical speed of 480Mbps.It’s also referred to as “Full Speed” USB, which can be confusing. These old devices will work with current modern USB, but at no more than that speed and usually a lower one. USB 1 has a maximum theoretical speed of 12Mbps (megabits per second).Right now there are three generations of USB out in the wild, with a fourth as yet unreleased, but in the works. That means the computer, the cable and the device must all comply with that particular USB standard for it to run as well as possible. When you buy a USB peripheral, it will specify which the highest standard is that it supports and – sometimes – requires. Which means that some devices simply won’t work properly because they can’t push data through the cable quickly enough. The worst that can happen is that it defaults to the oldest, slowest standard that both devices can understand. In practice this means that if a USB cable fits into a port, it will work. Yet, a key part of USB is the “universal” bit.

The hardware that sends and receives information is faster and the internal wiring differs significantly. That’s because USB standards have improved over the years.

It’s important to understand that although two USB ports and cables might look identical, it doesn’t mean they have the same capabilities.

Usb 2 vs usb 3 transfer speeds