ΔE 10.1, fair: the same colour family, but not a straight swap. Grunge Brown is a little darker, more saturated than Nomad Flesh.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 10). Grunge Brown is a little darker, more saturated than Nomad Flesh.
The same difference applies the other way round: Nomad Flesh is a little lighter, 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 Nomad Flesh on the colour wheel See Grunge Brown on the colour wheel
All matches: Nomad Flesh equivalents · Grunge Brown equivalents