ΔE 11.1, fair: the same colour family, but not a straight swap. Fiendish Yellow is a little darker, more muted than Peach.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 11). Fiendish Yellow is a little darker, more muted than Peach.
The same difference applies the other way round: Peach is a little lighter, more saturated.
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 Peach on the colour wheel See Fiendish Yellow on the colour wheel
All matches: Peach equivalents · Fiendish Yellow equivalents