ΔE 19.5, loose: different enough that you should pick on purpose. Cobalt Turquoise is noticeably darker, much more muted, warmer than Raging Sea. They are different kinds of paint: Army Painter Raging Sea is a one-coat contrast-style paint and Golden Cobalt Turquoise is an ink, glaze or transparent paint, so they won’t behave the same on the model even where the colour is close.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 20). Cobalt Turquoise is noticeably darker, much more muted, warmer than Raging Sea. They are different kinds of paint.
The same difference applies the other way round: Raging Sea is noticeably lighter, much 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.
See Raging Sea on the colour wheel See Cobalt Turquoise on the colour wheel
All matches: Raging Sea equivalents · Cobalt Turquoise equivalents