> I can tell the difference between 4k low bitrate and 4k high bitrate, 1080p and 720p are like mud to my eyes

The more interesting question is whether you can tell the difference between 720p and 4K at the same bitrate. Dividing that bitrate across more pixels usually results in a worse image at the higher resolution.

High-bitrate 720p generally looks better than low-bitrate 4K - it's not uncommon to find that a DVD looks better than the Netflix stream of the same content.

This stuff is so complicated and insane, that a 720p TV version from a decade ago can look better than a modern 4K Blu-ray release.

Case in point: Ghost in the Shell (1995)

http://comp.judging.it/index.php?seriesid=Koukaku%20Kidoutai...

Old TV version: http://comp.judging.it/content/Koukaku%20Kidoutai/4K-1/Judgm...

New 4K BD: http://comp.judging.it/content/Koukaku%20Kidoutai/4K-1/4K%20...