ΔE 12.9, fair: the same colour family, but not a straight swap. Olive Drab is a little darker, more muted, warmer than Drab Green.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 13). Olive Drab is a little darker, more muted, warmer than Drab Green.
The same difference applies the other way round: Drab 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 Drab Green on the colour wheel See Olive Drab on the colour wheel
All matches: Drab Green equivalents · Olive Drab equivalents