Apocalypse Sky vs Medium Flesh

How close are they?

ΔE 17.7, loose: different enough that you should pick on purpose. Medium Flesh is noticeably lighter, more muted, warmer than Apocalypse Sky.

Can I use Medium Flesh instead of Apocalypse Sky?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 18). Medium Flesh is noticeably lighter, more muted, warmer than Apocalypse Sky.

Can I use Apocalypse Sky instead of Medium Flesh?

The same difference applies the other way round: Apocalypse Sky is noticeably darker, more saturated, cooler.

ΔE is the colour difference between our two swatch estimates: under about 6 is close, over about 15 is loose. Real paints also differ in finish, coverage and how they thin, so test before you commit.