ArsTechnica has a good explanation about this: http://arstechnica.com/apple/2015/03/explaining-the-usb-3-1-gen-1-port-in-the-retina-macbook/ http://arstechnica

ArsTechnica has a good explanation about this: http://arstechnica.com/apple/2015/03/explaining-the-usb-3-1-gen-1-port-in-the-retina-macbook/ http://arstechnica.com/apple/2015/03/explaining-the-usb-3-1-... In short: "USB 3.1, by contrast, is a much smaller change—so much so that the USB 3.1 specification has actually absorbed the USB 3.0 spec. For whatever reason, this has led to some odd name changes. The 10Gbps version of USB 3.1 that you probably think of when you think about USB 3.1 is called “USB 3.1 Gen 2.”"