HDR stands for high dynamic range. HDR allows for deeper blacks and brighter whites this adds more contrast and depth to video content.
Control Center supports HDR.
Dolby Vision is Dolby's proprietary HDR technology, it’s mostly used in movies.
Control Center does not yet support Dolby Vision.
HLG stands for Hybrid Log- Gamma, which is an HDR standard developed by the BBC and NHK. HLG is supported by HDMI 2.0b, HVEC, VP9, H.264/MPEG-4 AVC. Services like BBC iplayer, Freeview play, Youtube and DirecTV support HLG.
Control Center does not yet support HLG.