Zephyr Pink vs Romeo/Juliet

How close are they?

ΔE 19.2, loose: different enough that you should pick on purpose. Romeo/Juliet is noticeably lighter, cooler than Zephyr Pink.

Can I use Romeo/Juliet instead of Zephyr Pink?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 19). Romeo/Juliet is noticeably lighter, cooler than Zephyr Pink.

Can I use Zephyr Pink instead of Romeo/Juliet?

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