ΔE 15.1, loose: different enough that you should pick on purpose. Sap Green is a little darker, cooler than Drab Green.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 15). Sap Green is a little darker, cooler than Drab Green.
The same difference applies the other way round: Drab Green is a little lighter, warmer.
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 Sap Green on the colour wheel
All matches: Drab Green equivalents · Sap Green equivalents