Topaz Skin vs Rust Brown

How close are they?

ΔE 7.7, close: similar, with a visible difference side by side. Rust Brown is a little darker, more muted than Topaz Skin.

Can I use Rust Brown instead of Topaz Skin?

Usually, if you are not matching paint already on the model. Close match (ΔE 8). Rust Brown is a little darker, more muted than Topaz Skin.

Can I use Topaz Skin instead of Rust Brown?

The same difference applies the other way round: Topaz Skin is a little lighter, more saturated.

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.