Corvus Black vs Nocturne Skin

How close are they?

ΔE 20.4, loose: different enough that you should pick on purpose. Nocturne Skin is noticeably lighter, more saturated than Corvus Black.

Can I use Nocturne Skin instead of Corvus Black?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 20). Nocturne Skin is noticeably lighter, more saturated than Corvus Black.

Can I use Corvus Black instead of Nocturne Skin?

The same difference applies the other way round: Corvus Black is noticeably darker, more muted.

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.