ΔE 5.2, very close: most people won’t see a difference side by side. Umber Ink is a little darker than Black Tone. They are different kinds of paint: Army Painter Black Tone is a wash/shade and Nocturna Models Umber Ink 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). Umber Ink is a little darker than Black Tone. They are different kinds of paint.
The same difference applies the other way round: Black Tone 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 Black Tone on the colour wheel See Umber Ink on the colour wheel
All matches: Black Tone equivalents · Umber Ink equivalents