ΔE 8.2, close: similar, with a visible difference side by side. Onyx Skin is a little lighter, cooler than Chipping.
Usually, if you are not matching paint already on the model. Close match (ΔE 8). Onyx Skin is a little lighter, cooler than Chipping.
The same difference applies the other way round: Chipping is a little darker, 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 Chipping on the colour wheel See Onyx Skin on the colour wheel
All matches: Chipping equivalents · Onyx Skin equivalents