ΔE 18.8, loose: different enough that you should pick on purpose. Waaagh! Flesh is noticeably darker, warmer than Emerald Scream.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 19). Waaagh! Flesh is noticeably darker, warmer than Emerald Scream.
The same difference applies the other way round: Emerald Scream is noticeably lighter, 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.
See Emerald Scream on the colour wheel See Waaagh! Flesh on the colour wheel
All matches: Emerald Scream equivalents · Waaagh! Flesh equivalents