ΔE 8.9, close: similar, with a visible difference side by side. Chestnut Brown is more saturated than Purple Black.
Usually, if you are not matching paint already on the model. Close match (ΔE 9). Chestnut Brown is more saturated than Purple Black.
The same difference applies the other way round: Purple Black 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 Purple Black on the colour wheel See Chestnut Brown on the colour wheel
All matches: Purple Black equivalents · Chestnut Brown equivalents