ΔE 7.2, close: similar, with a visible difference side by side. Abyssal Blue is a little darker, more saturated than Night Blue.
Usually, if you are not matching paint already on the model. Close match (ΔE 7). Abyssal Blue is a little darker, more saturated than Night Blue.
The same difference applies the other way round: Night Blue is a little lighter, more muted.
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 Night Blue on the colour wheel See Abyssal Blue on the colour wheel
All matches: Night Blue equivalents · Abyssal Blue equivalents