ΔE 9.6, close: similar, with a visible difference side by side. Olive Drab 1 is a little lighter, more saturated, warmer than Dark DAK Green.
Usually, if you are not matching paint already on the model. Close match (ΔE 10). Olive Drab 1 is a little lighter, more saturated, warmer than Dark DAK Green.
The same difference applies the other way round: Dark DAK Green is a little darker, 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 Dark DAK Green on the colour wheel See Olive Drab 1 on the colour wheel
All matches: Dark DAK Green equivalents · Olive Drab 1 equivalents