Hexwraith Flame vs Orc Skin

How close are they?

ΔE 25.1, loose: different enough that you should pick on purpose. Orc Skin is noticeably darker, more muted, warmer than Hexwraith Flame.

Can I use Orc Skin instead of Hexwraith Flame?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 25). Orc Skin is noticeably darker, more muted, warmer than Hexwraith Flame.

Can I use Hexwraith Flame instead of Orc Skin?

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