Royal Blue vs Mediterranean Blue

How close are they?

ΔE 9.7, close: similar, with a visible difference side by side. Mediterranean Blue is a little lighter, cooler than Royal Blue.

Can I use Mediterranean Blue instead of Royal Blue?

Usually, if you are not matching paint already on the model. Close match (ΔE 10). Mediterranean Blue is a little lighter, cooler than Royal Blue.

Can I use Royal Blue instead of Mediterranean Blue?

The same difference applies the other way round: Royal Blue is a little 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.