ΔE 13.3, fair: the same colour family, but not a straight swap. Jade Green is cooler than Necrotic Flesh. They are different kinds of paint: Army Painter Necrotic Flesh is an opaque base/layer paint and Green Stuff World Jade Green is an ink, glaze or transparent 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 13). Jade Green is cooler than Necrotic Flesh. They are different kinds of paint.
The same difference applies the other way round: Necrotic Flesh is 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 Necrotic Flesh on the colour wheel See Jade Green on the colour wheel
All matches: Necrotic Flesh equivalents · Jade Green equivalents