ΔE 15.9, loose: different enough that you should pick on purpose. Militarum Green is a little darker, more muted, cooler than Desolate Brown.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 16). Militarum Green is a little darker, more muted, cooler than Desolate Brown.
The same difference applies the other way round: Desolate Brown is a little lighter, more saturated, 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 Desolate Brown on the colour wheel See Militarum Green on the colour wheel
All matches: Desolate Brown equivalents · Militarum Green equivalents