Caribbean Ocean vs Cool Blue

How close are they?

ΔE 22.3, loose: different enough that you should pick on purpose. Cool Blue is noticeably darker, more muted, warmer than Caribbean Ocean.

Can I use Cool Blue instead of Caribbean Ocean?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 22). Cool Blue is noticeably darker, more muted, warmer than Caribbean Ocean.

Can I use Caribbean Ocean instead of Cool Blue?

The same difference applies the other way round: Caribbean Ocean is noticeably lighter, more saturated, cooler.

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.