ΔE 16.6, loose: different enough that you should pick on purpose. Scarlet Red is noticeably darker, more saturated, cooler than Rust Orange.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 17). Scarlet Red is noticeably darker, more saturated, cooler than Rust Orange.
The same difference applies the other way round: Rust Orange is noticeably lighter, 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.
See Rust Orange on the colour wheel See Scarlet Red on the colour wheel
All matches: Rust Orange equivalents · Scarlet Red equivalents