ΔE 6.4, close: similar, with a visible difference side by side. Medium Blue is more saturated, cooler than Blue.
Usually, if you are not matching paint already on the model. Close match (ΔE 6). Medium Blue is more saturated, cooler than Blue.
The same difference applies the other way round: Blue is 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.
See Blue on the colour wheel See Medium Blue on the colour wheel
All matches: Blue equivalents · Medium Blue equivalents