ΔE 8.7, close: similar, with a visible difference side by side. Dark Rust is more muted, cooler than Black Red.
Usually, if you are not matching paint already on the model. Close match (ΔE 9). Dark Rust is more muted, cooler than Black Red.
The same difference applies the other way round: Black Red is more saturated, 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 Black Red on the colour wheel See Dark Rust on the colour wheel
All matches: Black Red equivalents · Dark Rust equivalents