ΔE 8.3, close: similar, with a visible difference side by side. Black Metal is a little lighter, more muted than Night Scales.
Usually, if you are not matching paint already on the model. Close match (ΔE 8). Black Metal is a little lighter, more muted than Night Scales.
The same difference applies the other way round: Night Scales is a little darker, more saturated.
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 Scales on the colour wheel See Black Metal on the colour wheel
All matches: Night Scales equivalents · Black Metal equivalents