ΔE 8.6, close: similar, with a visible difference side by side. Navy Blue is a little lighter, cooler than Blue Black.
Usually, if you are not matching paint already on the model. Close match (ΔE 9). Navy Blue is a little lighter, cooler than Blue Black.
The same difference applies the other way round: Blue Black 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.
See Blue Black on the colour wheel See Navy Blue on the colour wheel
All matches: Blue Black equivalents · Navy Blue equivalents