ΔE 11.9, fair: the same colour family, but not a straight swap. Nurgling Green is a little darker, more muted, warmer than Matt Goblin Green. They are different kinds of paint: AMMO by Mig Matt Goblin Green is an ink, glaze or transparent paint and Citadel Nurgling Green 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 12). Nurgling Green is a little darker, more muted, warmer than Matt Goblin Green. They are different kinds of paint.
The same difference applies the other way round: Matt Goblin 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 Goblin Green on the colour wheel See Nurgling Green on the colour wheel
All matches: Matt Goblin Green equivalents · Nurgling Green equivalents