What's the advantage of USB 3.0 compared with USB 2.0?

USB 3.0 SuperSpeed

Both USB 2.0 and USB 3.0 supports three different speed levels for compatibility. USB 3.0 has additional “SuperSpeed” level which operates at the rate of 5 Gb/s (640 MB/s). There were rumors initially about USB 3.0 that, it’s using fiber optic cables. But that’s not true. It manages “SuperSpeed” with the help of additional pins in the connector.

Power Saving Mode

USB 2.0 can only connect 127 devices at a time and need to poll them to start communicating with devices. USB 3.0 will use a new method, something like “Ping” in which device will communicate to USB for use. This will save power and bandwidth.

USB 3.0 v/s USB 2.0 : Speed Comparison Chart