Hydra Turquoise vs Ray Gun Glow

How close are they?

ΔE 15.9, loose: different enough that you should pick on purpose. Ray Gun Glow is noticeably lighter, cooler than Hydra Turquoise.

Can I use Ray Gun Glow instead of Hydra Turquoise?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 16). Ray Gun Glow is noticeably lighter, cooler than Hydra Turquoise.

Can I use Hydra Turquoise instead of Ray Gun Glow?

The same difference applies the other way round: Hydra Turquoise is noticeably darker, 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.