Catachan Flesh vs Brown (JGSDF)

How close are they?

ΔE 8.2, close: similar, with a visible difference side by side. Brown (JGSDF) is cooler than Catachan Flesh.

Can I use Brown (JGSDF) instead of Catachan Flesh?

Usually, if you are not matching paint already on the model. Close match (ΔE 8). Brown (JGSDF) is cooler than Catachan Flesh.

Can I use Catachan Flesh instead of Brown (JGSDF)?

The same difference applies the other way round: Catachan Flesh is 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.