ΔE 4.0, very close: most people won’t see a difference side by side. Black Legion is a little lighter than Black Uniform Base. They are different kinds of paint: AK Interactive Black Uniform Base is an opaque base/layer paint and Citadel Black Legion is a one-coat contrast-style 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 4). Black Legion is a little lighter than Black Uniform Base. They are different kinds of paint.
The same difference applies the other way round: Black Uniform Base 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 Black Uniform Base on the colour wheel See Black Legion on the colour wheel
All matches: Black Uniform Base equivalents · Black Legion equivalents