ΔE 17.2, loose: different enough that you should pick on purpose. Faded Plum is a little darker, more muted, cooler than Fey Pink.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 17). Faded Plum is a little darker, more muted, cooler than Fey Pink.
The same difference applies the other way round: Fey Pink is a little 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 Fey Pink on the colour wheel See Faded Plum on the colour wheel
All matches: Fey Pink equivalents · Faded Plum equivalents