ΔE 23.2, loose: different enough that you should pick on purpose. Skeleton Brown is noticeably darker, more muted, warmer than Militarum Green.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 23). Skeleton Brown is noticeably darker, more muted, warmer than Militarum Green.
The same difference applies the other way round: Militarum Green is noticeably 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 Militarum Green on the colour wheel See Skeleton Brown on the colour wheel
All matches: Militarum Green equivalents · Skeleton Brown equivalents