Check out the "Words for Nerds" sections at https://www.hisense-usa.com/electronics/tv/50h8c and https://www.hisense-usa.com/electronics/tv/50h6c. Basically, the H8C is a slightly higher end model than the H6C. The main extras the H8C seems to have are:
- local dimming
- an ethernet port
- Dolby Digital support
- Hisense "Himedia" and "AirBridge" support (sounds like Google Cast)