Grey Green vs Pestilent Flesh

How close are they?

ΔE 9.6, close: similar, with a visible difference side by side. Pestilent Flesh is more saturated than Grey Green.

Can I use Pestilent Flesh instead of Grey Green?

Usually, if you are not matching paint already on the model. Close match (ΔE 10). Pestilent Flesh is more saturated than Grey Green.

Can I use Grey Green instead of Pestilent Flesh?

The same difference applies the other way round: Grey Green is 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.