USB 2.0 vs. USB 3.0

 

USB 3.0 provides better speed and more efficient power management than USB 2.0. USB 3.0 is backward compatible with USB 2.0 devices; however, data transfer speeds are limited to USB 2.0 levels when these devices inter-operate. In 2014, a new standard, USB 3.1, was released and is expected to be in widespread use by 2015.

Comparison chart

Released	April 2000	November 2008
Speed	High Speed or HS, 480 Mbps (Megabits per second)	10 times faster than USB 2.0. Super Speed or SS, 4.8 Gbps (Giga bits per second)
Signaling Method	Polling mechanism i.e can either send or receive data (Half duplex)	Asynchronous mechanism i.e. can send and receive data simultaneously (Full duplex)
Price	For a similar product, the USB 2.0 version is generally less expensive than it's USB 3.0 version.	For a similar product, the USB 3.0 version is generally more expensive than it's USB 2.0 version.
Power Usage	Up to 500 mA	Up to 900 mA. Allows better power efficiency with less power for idle states. Can power more devices from one hub.
Number of wires within the cable	4	9
Standard-A Connectors	Grey in color	Blue in color
Standard-B Connectors	Smaller in size	Extra space for more wires
Max Cable length	5 meters	3 meters

USB 3.0 provides better speed and more efficient power management than USB 2.0. USB 3.0 is backward compatible with USB 2.0 devices; however, data transfer speeds are limited to USB 2.0 levels when these devices inter-operate. In 2014, a new standard, USB 3.1, was released and is expected to be in widespread use by 2015.