What does this mean? The "retina" resolutions are all over the place and depend on the device size and type. Also they seem to always be somewhere in the middle of pc options, e.g. for the macbook air 13 you have 1920x1200 (average pc) < 2560x1664 (air or expensive pc) < 3840x2400 (overkill pc). For your example at 27" that seems to be 4k (average pc) < 5k (studio display) < 6k (dell etc.) < 8k (overkill).
What does this mean? The "retina" resolutions are all over the place and depend on the device size and type. Also they seem to always be somewhere in the middle of pc options, e.g. for the macbook air 13 you have 1920x1200 (average pc) < 2560x1664 (air or expensive pc) < 3840x2400 (overkill pc). For your example at 27" that seems to be 4k (average pc) < 5k (studio display) < 6k (dell etc.) < 8k (overkill).