Crystal Blue vs Andrea Blue

How close are they?

ΔE 7.4, close: similar, with a visible difference side by side. Andrea Blue is more muted, cooler than Crystal Blue.

Can I use Andrea Blue instead of Crystal Blue?

Usually, if you are not matching paint already on the model. Close match (ΔE 7). Andrea Blue is more muted, cooler than Crystal Blue.

Can I use Crystal Blue instead of Andrea Blue?

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