ΔE 3.8, very close: most people won’t see a difference side by side. Matt White Primer is a little darker than Titanium White INK. They are different kinds of paint: AK Interactive Titanium White INK is an ink, glaze or transparent paint and Army Painter Matt White Primer is a technical paint or medium, 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). Matt White Primer is a little darker than Titanium White INK. They are different kinds of paint.
The same difference applies the other way round: Titanium White INK is a little lighter.
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 Titanium White INK on the colour wheel See Matt White Primer on the colour wheel
All matches: Titanium White INK equivalents · Matt White Primer equivalents