Gum Pink vs Fey Pink

How close are they?

ΔE 15.9, loose: different enough that you should pick on purpose. Fey Pink is noticeably darker, more saturated, cooler than Gum Pink.

Can I use Fey Pink instead of Gum Pink?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 16). Fey Pink is noticeably darker, more saturated, cooler than Gum Pink.

Can I use Gum Pink instead of Fey Pink?

The same difference applies the other way round: Gum Pink is noticeably lighter, more muted, 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.