Blue Sand vs Hydra Turquoise

How close are they?

ΔE 28.3, loose: different enough that you should pick on purpose. Hydra Turquoise is a little darker, more saturated, cooler than Blue Sand.

Can I use Hydra Turquoise instead of Blue Sand?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 28). Hydra Turquoise is a little darker, more saturated, cooler than Blue Sand.

Can I use Blue Sand instead of Hydra Turquoise?

The same difference applies the other way round: Blue Sand is a little lighter, more muted, 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.