ΔE 9.8, close: similar, with a visible difference side by side. IJA Grey Green is a little darker, more muted, warmer than Medium Green.
Usually, if you are not matching paint already on the model. Close match (ΔE 10). IJA Grey Green is a little darker, more muted, warmer than Medium Green.
The same difference applies the other way round: Medium 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 Medium Green on the colour wheel See IJA Grey Green on the colour wheel
All matches: Medium Green equivalents · IJA Grey Green equivalents