The first generation Thunderbolt™ is limited to one independent 10Gbs bi-directional channel each for data and display.
|How it works||Thunderbolt™ Cables|
Thunderbolt™ 2 will enable 4K video file transfer and display simultaneously by combining the two previously independent 10Gbs channels into one 20Gbs bi-directional channel.
Thunderbolt™ 2 supports DisplayPort 1.2, which means it is possible to stream video to a single 4K monitor or dual QHD monitors.
There are no new cables required for use with Thunderbolt™ 2 as it utilizes the same Thunderbolt™ cables and connectors as the first generation.