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