ΔE 10.3, fair: the same colour family, but not a straight swap. Fluor Green is a little lighter, warmer than Ghoul Green. They are different kinds of paint: Army Painter Ghoul Green is a one-coat contrast-style paint and Green Stuff World Fluor 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 10). Fluor Green is a little lighter, warmer than Ghoul Green. They are different kinds of paint.
The same difference applies the other way round: Ghoul Green is a little darker, 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 Ghoul Green on the colour wheel See Fluor Green on the colour wheel
All matches: Ghoul Green equivalents · Fluor Green equivalents