ΔE 4.3, very close: most people won’t see a difference side by side. Opulentus Black is more saturated than Dark Olive. They are different kinds of paint: Army Painter Dark Olive is an opaque base/layer paint and Green Stuff World Opulentus Black 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 4). Opulentus Black is more saturated than Dark Olive. They are different kinds of paint.
The same difference applies the other way round: Dark Olive is more muted.
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 Dark Olive on the colour wheel See Opulentus Black on the colour wheel
All matches: Dark Olive equivalents · Opulentus Black equivalents