ΔE 15.8, loose: different enough that you should pick on purpose. Orange Brown is a little darker, more saturated, warmer than Ratskin 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 Ratskin Flesh.
The same difference applies the other way round: Ratskin 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.
See Ratskin Flesh on the colour wheel See Orange Brown on the colour wheel
All matches: Ratskin Flesh equivalents · Orange Brown equivalents