Raging Sea vs Nighthaunt Gloom

How close are they?

ΔE 16.3, loose: different enough that you should pick on purpose. Nighthaunt Gloom is a little darker, much more muted, cooler than Raging Sea.

Can I use Nighthaunt Gloom instead of Raging Sea?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 16). Nighthaunt Gloom is a little darker, much more muted, cooler than Raging Sea.

Can I use Raging Sea instead of Nighthaunt Gloom?

The same difference applies the other way round: Raging Sea is a little lighter, much 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.