ΔE 9.0, close: similar, with a visible difference side by side. Olive Brown is a little lighter, more muted than Chocolate (Chipping).
Usually, if you are not matching paint already on the model. Close match (ΔE 9). Olive Brown is a little lighter, more muted than Chocolate (Chipping).
The same difference applies the other way round: Chocolate (Chipping) is a little darker, more saturated.
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 Chocolate (Chipping) on the colour wheel See Olive Brown on the colour wheel
All matches: Chocolate (Chipping) equivalents · Olive Brown equivalents