Raging Sea vs Blue Glacier

How close are they?

ΔE 16.0, loose: different enough that you should pick on purpose. Blue Glacier is a little lighter, more muted, cooler than Raging Sea.

Can I use Blue Glacier instead of Raging Sea?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 16). Blue Glacier is a little lighter, more muted, cooler than Raging Sea.

Can I use Raging Sea instead of Blue Glacier?

The same difference applies the other way round: Raging Sea is a little darker, more saturated, 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.