ΔE 36.1, loose: different enough that you should pick on purpose. Ink Red is noticeably darker, more muted, cooler than Light Rust.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 36). Ink Red is noticeably darker, more muted, cooler than Light Rust.
The same difference applies the other way round: Light Rust is noticeably lighter, 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 Light Rust on the colour wheel See Ink Red on the colour wheel
All matches: Light Rust equivalents · Ink Red equivalents