ΔE 7.7, close: similar, with a visible difference side by side. Cocoa Brown is a little darker, warmer than Grimoire Purple.
Usually, if you are not matching paint already on the model. Close match (ΔE 8). Cocoa Brown is a little darker, warmer than Grimoire Purple.
The same difference applies the other way round: Grimoire Purple is a little lighter, 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 Grimoire Purple on the colour wheel See Cocoa Brown on the colour wheel
All matches: Grimoire Purple equivalents · Cocoa Brown equivalents