ΔE 8.9, close: similar, with a visible difference side by side. Flat Blue is a little lighter than Night Lords Blue.
Usually, if you are not matching paint already on the model. Close match (ΔE 9). Flat Blue is a little lighter than Night Lords Blue.
The same difference applies the other way round: Night Lords Blue is a little darker.
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 Lords Blue on the colour wheel See Flat Blue on the colour wheel
All matches: Night Lords Blue equivalents · Flat Blue equivalents