ΔE 20.2, loose: different enough that you should pick on purpose. Evil Flesh is noticeably darker, more saturated than Ash Grey.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 20). Evil Flesh is noticeably darker, more saturated than Ash Grey.
The same difference applies the other way round: Ash Grey is noticeably lighter, more muted.
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 Ash Grey on the colour wheel See Evil Flesh on the colour wheel
All matches: Ash Grey equivalents · Evil Flesh equivalents