Good question! Had to look it up myself. It looks like it is just a more efficient protocol to save on data. Anyway this is what I found. 
What is High-Efficiency Video Coding (HEVC)?
High-Efficiency Video Coding (HEVC), also known as H 265, is a new video compression standard designed to offer improved video quality and a higher average bitratereduction.
HEVC format support is becoming more common in many devices, including mobile devices and content capture systems. This is because HEVC codec can offer the same quality video at a lower bitrate or higher quality video at the same bitrate. This makes it a great choice for streaming video, as it can reduce file size while maintaining high quality.
HEVC is a powerful video compression technology. It can help improve the quality of video streams while reducing the file size. This makes it a great choice for anyone who streams live video.