A:Answer They are 2 seperate features.
If you play 4k games a few feet from the screen, you'll get the benefit of 4k, but beyond that the human eye can't differentiate.
HDR will benefit regardless of distance, as it adds more gradient to colors, and brighter lighting highlights (think sunlight coming through a window into a dark room). How much you benefit will also be dependent on the brightness level of the screen, and of course both the game and the screen have to support HDR. A 10-bit screen (req for HDR 10 std; Dolby Vision req. 12 bit) can have more detail in the bright areas of the image, and/or more details in the dark parts of the image. It can also have a greater range between the brightest and darkest parts of the image, reducing the "banding" you can see when the image goes from dark to light. This is because standard 8 bit TV will display a bit over 16 million colors and the human eye is capable of seeing much more. A 10 bit display by comparison can display over a billion different shades of color.
