ΔE 15.5, loose: different enough that you should pick on purpose. Ryza Rust is a little lighter, much more saturated, cooler than Warm Yellow.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 16). Ryza Rust is a little lighter, much more saturated, cooler than Warm Yellow.
The same difference applies the other way round: Warm Yellow is a little darker, much 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 Warm Yellow on the colour wheel See Ryza Rust on the colour wheel
All matches: Warm Yellow equivalents · Ryza Rust equivalents