What is the difference between these two modes?
Samsung's MU 2017 models have the HDR+ mode in the picture settings menu whereas the NU 2018 models (most of them) doesn't.
HDR+ on your TV is a faux HDR effect mate, It attempts to map the current source into the native range of the panel. Invariably this leads to an unatural oversaturation of colours, also the extra brightness increases the likleyhood of other issues such as haloing.
The only way it would add extra detail to the scene would be because the TV was poorly calibrated in SDR mode.
I would recommend leaving it off
Gonna be frank, I'm seeing a lot of conflicting details.
On the one hand, it seems to add a faux HDR effect for SDR content, HOWEVER it seems to be better for actual HDR content.
Can anyone confirm if this is the case? Comparing it to my friends Dolby Vision HDR T.V. it looks comparable with it on when playing, say, Resident Evil 2. I'm going to compare with Odyssey next since that uses actual lumens in it. I know that the Samsung gets about 900 lumens with it off compared to almost 2000 on the other TV. (Or maybe it was 100 vs 900. Mine was a smaller amount I know that).
Gonna test a bit
Samsungs description is "automatically provide an optimal HDR effect based on the video source"
key word being effect, ie additional processing. It is a picture processing "enhancement" nothing more.
console games do not use Dolby vision so that bit is kind of irelevent in this context.
Also alot of console games are not even HDR
this is for red dead redemption 2 go to 10 mins in
as you can see its its an SDR 8 bit image placed in a HDR container.
The Resident Evil Remake is the same
It is recommended to play these games with HDR turned off so I am not surprised it looks comparable