Guide to HEVC/H.265 Encoding and Playback
 

HEVC's main advantage over H.264 is that it offers roughly double the compression ratio for the same quality. This means that a video file encoded with HEVC can occupy half the space of its H.264 equivalent with no noticeable change in quality, or the same amount of space with improved quality.

http://www.techspot.com/article/1131...ding-playback/