Sand FS 33531 vs Deepkin Flesh

How close are they?

ΔE 6.4, close: similar, with a visible difference side by side. Deepkin Flesh is more saturated, warmer than Sand FS 33531.

Can I use Deepkin Flesh instead of Sand FS 33531?

Usually, if you are not matching paint already on the model. Close match (ΔE 6). Deepkin Flesh is more saturated, warmer than Sand FS 33531.

Can I use Sand FS 33531 instead of Deepkin Flesh?

The same difference applies the other way round: Sand FS 33531 is 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.