Nomad Flesh vs Orange Brown

How close are they?

ΔE 16.5, loose: different enough that you should pick on purpose. Orange Brown is a little darker, more saturated, warmer than Nomad Flesh.

Can I use Orange Brown instead of Nomad Flesh?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 16). Orange Brown is a little darker, more saturated, warmer than Nomad Flesh.

Can I use Nomad Flesh instead of Orange Brown?

The same difference applies the other way round: Nomad Flesh is a little lighter, more muted, 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.