4K to 8K (and for that matter 30fps to 60fps+) is REALLY noticeable in VR video.
Normal video, not so much.
Does anyone even consider VR below 90 FPS? Sounds like a miserable experience.
But yes, for resolution the angular pixel size is what matters and since VR covers more of your field of view you also need more pixels for the same results.
The starting to point really does matter.
Resolutions are actually good example of things at low end(today) scale. 1920x1080 * 24 bits = 6220800 bytes. So 6 megs. Just to store 16 million colour screen state.