Zephyr Pink vs Galaxia

How close are they?

ΔE 43.3, loose: different enough that you should pick on purpose. Galaxia is noticeably darker, cooler than Zephyr Pink.

Can I use Galaxia instead of Zephyr Pink?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 43). Galaxia is noticeably darker, cooler than Zephyr Pink.

Can I use Zephyr Pink instead of Galaxia?

The same difference applies the other way round: Zephyr Pink is noticeably lighter, 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.