ΔE 7.1, close: similar, with a visible difference side by side. Light Rust is more muted, warmer than Brutal Brown.
Usually, if you are not matching paint already on the model. Close match (ΔE 7). Light Rust is more muted, warmer than Brutal Brown.
The same difference applies the other way round: Brutal Brown is more saturated, cooler.
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 Brutal Brown on the colour wheel See Light Rust on the colour wheel
All matches: Brutal Brown equivalents · Light Rust equivalents