ΔE 7.0, close: similar, with a visible difference side by side. Chestnut Brown is a little lighter, more saturated than Arbuckles Brown.
Usually, if you are not matching paint already on the model. Close match (ΔE 7). Chestnut Brown is a little lighter, more saturated than Arbuckles Brown.
The same difference applies the other way round: Arbuckles Brown is a little darker, 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 Arbuckles Brown on the colour wheel See Chestnut Brown on the colour wheel
All matches: Arbuckles Brown equivalents · Chestnut Brown equivalents