Earth Brown vs Ratskin Flesh

How close are they?

ΔE 15.4, loose: different enough that you should pick on purpose. Ratskin Flesh is noticeably lighter, more muted than Earth Brown.

Can I use Ratskin Flesh instead of Earth Brown?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 15). Ratskin Flesh is noticeably lighter, more muted than Earth Brown.

Can I use Earth Brown instead of Ratskin Flesh?

The same difference applies the other way round: Earth Brown is noticeably darker, more saturated.

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.