ΔE 7.2, close: similar, with a visible difference side by side. Matt Black Primer is a little lighter, more muted than Sepia INK. They are different kinds of paint: AK Interactive Sepia INK is an ink, glaze or transparent paint and Army Painter Matt Black Primer is a technical paint or medium, 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 7). Matt Black Primer is a little lighter, more muted than Sepia INK. They are different kinds of paint.
The same difference applies the other way round: Sepia INK 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 Sepia INK on the colour wheel See Matt Black Primer on the colour wheel
All matches: Sepia INK equivalents · Matt Black Primer equivalents