Orange Brown vs Rust

How close are they?

ΔE 7.6, close: similar, with a visible difference side by side. Rust is more saturated, cooler than Orange Brown.

Can I use Rust instead of Orange Brown?

Usually, if you are not matching paint already on the model. Close match (ΔE 8). Rust is more saturated, cooler than Orange Brown.

Can I use Orange Brown instead of Rust?

The same difference applies the other way round: Orange Brown is more muted, 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.