Ryza Rust vs Yellow FS13538

How close are they?

ΔE 13.7, fair: the same colour family, but not a straight swap. Yellow FS13538 is a little lighter, much more saturated than Ryza Rust.

Can I use Yellow FS13538 instead of Ryza Rust?

Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 14). Yellow FS13538 is a little lighter, much more saturated than Ryza Rust.

Can I use Ryza Rust instead of Yellow FS13538?

The same difference applies the other way round: Ryza Rust is a little darker, much more muted.

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.