Cloud Sea vs Light Blue Green

How close are they?

ΔE 19.4, loose: different enough that you should pick on purpose. Light Blue Green is noticeably lighter, more saturated, cooler than Cloud Sea.

Can I use Light Blue Green instead of Cloud Sea?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 19). Light Blue Green is noticeably lighter, more saturated, cooler than Cloud Sea.

Can I use Cloud Sea instead of Light Blue Green?

The same difference applies the other way round: Cloud Sea is noticeably darker, 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.