ΔE 16.4, loose: different enough that you should pick on purpose. Rust Brown is more muted, cooler than Fresh Rust.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 16). Rust Brown is more muted, cooler than Fresh Rust.
The same difference applies the other way round: Fresh Rust 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 Fresh Rust on the colour wheel See Rust Brown on the colour wheel
All matches: Fresh Rust equivalents · Rust Brown equivalents