ΔE 14.1, fair: the same colour family, but not a straight swap. Yellow FS33531 is a little darker, more muted, warmer than Imp Yellow.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 14). Yellow FS33531 is a little darker, more muted, warmer than Imp Yellow.
The same difference applies the other way round: Imp Yellow is a little lighter, 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 Imp Yellow on the colour wheel See Yellow FS33531 on the colour wheel
All matches: Imp Yellow equivalents · Yellow FS33531 equivalents