Caribbean Ocean vs Green Shark Skin

How close are they?

ΔE 31.9, loose: different enough that you should pick on purpose. Green Shark Skin is noticeably darker, more muted than Caribbean Ocean.

Can I use Green Shark Skin instead of Caribbean Ocean?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 32). Green Shark Skin is noticeably darker, more muted than Caribbean Ocean.

Can I use Caribbean Ocean instead of Green Shark Skin?

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