ΔE 9.8, close: similar, with a visible difference side by side. Bone Black is a little darker, more muted than Boot Brown.
Usually, if you are not matching paint already on the model. Close match (ΔE 10). Bone Black is a little darker, more muted than Boot Brown.
The same difference applies the other way round: Boot Brown is a little lighter, 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 Boot Brown on the colour wheel See Bone Black on the colour wheel
All matches: Boot Brown equivalents · Bone Black equivalents