ΔE 30.7, loose: different enough that you should pick on purpose. Fairy Skin is noticeably lighter, much more muted than Crimson.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 31). Fairy Skin is noticeably lighter, much more muted than Crimson.
The same difference applies the other way round: Crimson is noticeably darker, much 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 Crimson on the colour wheel See Fairy Skin on the colour wheel
All matches: Crimson equivalents · Fairy Skin equivalents