Darkoath Flesh vs Dwarf Skin

How close are they?

ΔE 26.2, loose: different enough that you should pick on purpose. Dwarf Skin is noticeably darker, more muted, cooler than Darkoath Flesh.

Can I use Dwarf Skin instead of Darkoath Flesh?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 26). Dwarf Skin is noticeably darker, more muted, cooler than Darkoath Flesh.

Can I use Darkoath Flesh instead of Dwarf Skin?

The same difference applies the other way round: Darkoath Flesh is noticeably lighter, more saturated, 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.