ΔE 5.6, very close: most people won’t see a difference side by side. Ink Black Green is cooler than Midnight Olive. They are different kinds of paint: Army Painter Midnight Olive is an opaque base/layer paint and Vallejo Ink Black Green 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 6). Ink Black Green is cooler than Midnight Olive. They are different kinds of paint.
The same difference applies the other way round: Midnight Olive is 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 Midnight Olive on the colour wheel See Ink Black Green on the colour wheel
All matches: Midnight Olive equivalents · Ink Black Green equivalents