Umbral Umber vs Dark Rust

How close are they?

ΔE 9.3, close: similar, with a visible difference side by side. Dark Rust is a little lighter, cooler than Umbral Umber.

Can I use Dark Rust instead of Umbral Umber?

Usually, if you are not matching paint already on the model. Close match (ΔE 9). Dark Rust is a little lighter, cooler than Umbral Umber.

Can I use Umbral Umber instead of Dark Rust?

The same difference applies the other way round: Umbral Umber 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.