Flesh Wash vs Red Wash

How close are they?

ΔE 26.1, loose: different enough that you should pick on purpose. Red Wash is a little lighter, much more saturated, cooler than Flesh Wash.

Can I use Red Wash instead of Flesh Wash?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 26). Red Wash is a little lighter, much more saturated, cooler than Flesh Wash.

Can I use Flesh Wash instead of Red Wash?

The same difference applies the other way round: Flesh Wash is a little darker, much more muted, warmer.

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.