ΔE 14.1, fair: the same colour family, but not a straight swap. Pestilent Flesh is a little darker, more muted, warmer than Matt Military Green. They are different kinds of paint: AMMO by Mig Matt Military Green is an ink, glaze or transparent paint and Army Painter Pestilent Flesh is an opaque base/layer paint, so they won’t behave the same on the model even where the colour is close.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 14). Pestilent Flesh is a little darker, more muted, warmer than Matt Military Green. They are different kinds of paint.
The same difference applies the other way round: Matt Military Green is a little lighter, 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.
See Matt Military Green on the colour wheel See Pestilent Flesh on the colour wheel
All matches: Matt Military Green equivalents · Pestilent Flesh equivalents