ΔE 8.8, close: similar, with a visible difference side by side. Succubus Skin is a little lighter, cooler than Rust Brown.
Usually, if you are not matching paint already on the model. Close match (ΔE 9). Succubus Skin is a little lighter, cooler than Rust Brown.
The same difference applies the other way round: Rust Brown is a little darker, 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.
See Rust Brown on the colour wheel See Succubus Skin on the colour wheel
All matches: Rust Brown equivalents · Succubus Skin equivalents