USB 2.0: Older version, compatible with almost all devices but with slower data transfer speed (480Mbit/s.) than newer versions.
USB 3.0: Faster data transfer (5 Gbit/s) than USB 2.0 when connected to a USB 3.0 port. Compatible with older versions. Also referred to as USB 3.1 Gen 1 / 3.2 Gen 1.
USB 3.1: Faster data transfer (10 Gbit/s) than previous versions when connected to a USB 3.1 port. Compatible with older versions. Also referred to as USB 3.1 Gen 2 / 3.2 Gen 2.
USB 3.2: Faster data transfer (20 Gbit/s) than previous versions when connected to a USB 3.2 port. Compatible with older versions. Also referred to as USB 3.2 Gen 2x2.