ΔE 19.6, loose: different enough that you should pick on purpose. Slimer Green is more saturated, cooler than Pestilent Flesh.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 20). Slimer Green is more saturated, cooler than Pestilent Flesh.
The same difference applies the other way round: Pestilent Flesh is more muted, warmer.
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 Pestilent Flesh on the colour wheel See Slimer Green on the colour wheel
All matches: Pestilent Flesh equivalents · Slimer Green equivalents