ΔE 8.3, close: similar, with a visible difference side by side. IJA Grey Green is a little darker, cooler than Vampire Fang.
Usually, if you are not matching paint already on the model. Close match (ΔE 8). IJA Grey Green is a little darker, cooler than Vampire Fang.
The same difference applies the other way round: Vampire Fang is a little lighter, 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 Vampire Fang on the colour wheel See IJA Grey Green on the colour wheel
All matches: Vampire Fang equivalents · IJA Grey Green equivalents