ΔE 5.3, very close: most people won’t see a difference side by side. Blue is a little darker, warmer than Night Lords Blue. They are different kinds of paint: Citadel Night Lords Blue is an opaque base/layer paint and Green Stuff World Blue is an ink, glaze or transparent paint, so they won’t behave the same on the model even where the colour is close.
Yes, for most jobs. Very close match (ΔE 5). Blue is a little darker, warmer than Night Lords Blue. They are different kinds of paint.
The same difference applies the other way round: Night Lords Blue is a little lighter, cooler.
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 Blue on the colour wheel
All matches: Night Lords Blue equivalents · Blue equivalents