HTC promised to reveal a ‘very, very big breakthrough’ for this edition of the device and this appears to be present in the Vive Pre. It’s a redesigned HMD with a ‘brighter’ display and a front-facing camera that can integrate the real world into VR, allowing players to locate real world objects without needing to take the HMD off. The controllers have been redesigned too, including ‘updated ergonomics and softer edges, greater balance, new textured buttons, and grip pads for a more comfortable feel in the hand.’
http://vrfocus.com/archives/27414/htc-unveils-second-version-of-the-htc-vive/