ΔE 18.3, loose: different enough that you should pick on purpose. Steel Legion Drab is noticeably lighter, warmer than IDF Green.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 18). Steel Legion Drab is noticeably lighter, warmer than IDF Green.
The same difference applies the other way round: IDF Green is noticeably darker, 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 IDF Green on the colour wheel See Steel Legion Drab on the colour wheel
All matches: IDF Green equivalents · Steel Legion Drab equivalents