ΔE 8.0, close: similar, with a visible difference side by side. Shadow Thorn is more saturated, cooler than Night Blue. They are different kinds of paint: AMMO by Mig Night Blue is an ink, glaze or transparent paint and Army Painter Shadow Thorn is an opaque base/layer paint, so they won’t behave the same on the model even where the colour is close.
Usually, if you are not matching paint already on the model. Close match (ΔE 8). Shadow Thorn is more saturated, cooler than Night Blue. They are different kinds of paint.
The same difference applies the other way round: Night Blue is more muted, 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 Blue on the colour wheel See Shadow Thorn on the colour wheel
All matches: Night Blue equivalents · Shadow Thorn equivalents