ΔE 6.9, close: similar, with a visible difference side by side. Dark Gray 2 is a little lighter, cooler than Night Sky.
Usually, if you are not matching paint already on the model. Close match (ΔE 7). Dark Gray 2 is a little lighter, cooler than Night Sky.
The same difference applies the other way round: Night Sky 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 Night Sky on the colour wheel See Dark Gray 2 on the colour wheel
All matches: Night Sky equivalents · Dark Gray 2 equivalents