ΔE 9.6, close: similar, with a visible difference side by side. Olive Drab is a little darker, more saturated, warmer than Mid DAK Green.
Usually, if you are not matching paint already on the model. Close match (ΔE 10). Olive Drab is a little darker, more saturated, warmer than Mid DAK Green.
The same difference applies the other way round: Mid DAK Green is a little lighter, more muted, 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 Mid DAK Green on the colour wheel See Olive Drab on the colour wheel
All matches: Mid DAK Green equivalents · Olive Drab equivalents