Aqua Alchemy vs Adriatic Blue

How close are they?

ΔE 25.8, loose: different enough that you should pick on purpose. Adriatic Blue is a little darker, more muted, cooler than Aqua Alchemy.

Can I use Adriatic Blue instead of Aqua Alchemy?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 26). Adriatic Blue is a little darker, more muted, cooler than Aqua Alchemy.

Can I use Aqua Alchemy instead of Adriatic Blue?

The same difference applies the other way round: Aqua Alchemy is a little lighter, 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.