ΔE 9.0, close: similar, with a visible difference side by side. Amaranth Red is a little lighter, more saturated than Medium Rust.
Usually, if you are not matching paint already on the model. Close match (ΔE 9). Amaranth Red is a little lighter, more saturated than Medium Rust.
The same difference applies the other way round: Medium Rust is a little darker, more muted.
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 Medium Rust on the colour wheel See Amaranth Red on the colour wheel
All matches: Medium Rust equivalents · Amaranth Red equivalents