There are actually two distinct USB 3.1 specifications at this time. USB 3.1 Generation 1 was an initial upgrade to USB 3.0, but it is limited to 5Gbps data transfer speeds, while the newer USB 3.1 Generation 2 is the spec that boosts data transfer speeds to the theoretical 10Gbps.
USB 3.1 Gen 1 and Gen 2 vs. USB-C
Both USB 3.1 Gen 1 and USB 3.1 Gen 2 are increasingly being implemented along with USB Type-C (USB-C) ports in newer models of smartphones, tablets and laptops. The USB Type-C standard applies only to the physical plug connection, though, and the USB 3.1 data transfer and power standard can be used on existing USB Type-A and USB Type-B plugs as well as the newer USB-C plugs.
As with USB 3.0, USB 3.1 ports and cables offer backward-compatibility with previous USB standards, including USB 2.0 and USB 3.0. USB 3.1 also shares USB 3.0’s support of the USB Power Delivery specification, enabling USB 3.1 cables and ports to charge and power devices at a maximum of 20 volts at 5 amps for a total of 100 watts of power.
USB 3.1 Development and Availability
The USB Implementers Forum, a consortium of companies that includes Intel, Microsoft, Apple and HP, is responsible for the development of the USB 3.1 standard, and the forum first released the standard in 2013 as USB 3.1 Gen 1.
USB 3.1 Gen 1 and USB 3.1 Gen 2-supported devices didn’t start appearing until 2015, with the 2015 release of Apple’s MacBook. Widespread adoption by hardware manufacturers, especially for USB 3.1 Gen 2, is expected to continue to pick up in 2016 and beyond.
Note: USB 3.1 cables and ports are also sometimes referred to as SuperSpeed+ or SuperSpeed USB 10 Gbit/s in product literature.