ΔE 6.8, close: similar, with a visible difference side by side. March of the Fire Ants is a little lighter, warmer than Onyx Skin.
Usually, if you are not matching paint already on the model. Close match (ΔE 7). March of the Fire Ants is a little lighter, warmer than Onyx Skin.
The same difference applies the other way round: Onyx Skin is a little darker, cooler.
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 Onyx Skin on the colour wheel See March of the Fire Ants on the colour wheel
All matches: Onyx Skin equivalents · March of the Fire Ants equivalents