Chaotic Red vs Nocturne Skin

How close are they?

ΔE 9.4, close: similar, with a visible difference side by side. Nocturne Skin is a little darker, cooler than Chaotic Red.

Can I use Nocturne Skin instead of Chaotic Red?

Usually, if you are not matching paint already on the model. Close match (ΔE 9). Nocturne Skin is a little darker, cooler than Chaotic Red.

Can I use Chaotic Red instead of Nocturne Skin?

The same difference applies the other way round: Chaotic Red is a little lighter, 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.