Metallic Blue Green vs Hydra Turquoise

How close are they?

ΔE 7.4, close: similar, with a visible difference side by side. Hydra Turquoise is cooler than Metallic Blue Green.

Can I use Hydra Turquoise instead of Metallic Blue Green?

Usually, if you are not matching paint already on the model. Close match (ΔE 7). Hydra Turquoise is cooler than Metallic Blue Green.

Can I use Metallic Blue Green instead of Hydra Turquoise?

The same difference applies the other way round: Metallic Blue Green is 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.