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