Necrotic Flesh vs Moldy Skin

How close are they?

ΔE 7.0, close: similar, with a visible difference side by side. Moldy Skin is more saturated than Necrotic Flesh.

Can I use Moldy Skin instead of Necrotic Flesh?

Usually, if you are not matching paint already on the model. Close match (ΔE 7). Moldy Skin is more saturated than Necrotic Flesh.

Can I use Necrotic Flesh instead of Moldy Skin?

The same difference applies the other way round: Necrotic Flesh is 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.