ΔE 6.9, close: similar, with a visible difference side by side. Olive Grey is a little lighter, more muted than IDF Green.
Usually, if you are not matching paint already on the model. Close match (ΔE 7). Olive Grey is a little lighter, more muted than IDF Green.
The same difference applies the other way round: IDF Green is a little darker, more saturated.
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 IDF Green on the colour wheel See Olive Grey on the colour wheel
All matches: IDF Green equivalents · Olive Grey equivalents