ΔE 8.0, close: similar, with a visible difference side by side. Yellow Olive is a little lighter, more saturated than Black Brown.
Usually, if you are not matching paint already on the model. Close match (ΔE 8). Yellow Olive is a little lighter, more saturated than Black Brown.
The same difference applies the other way round: Black 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 Black Brown on the colour wheel See Yellow Olive on the colour wheel
All matches: Black Brown equivalents · Yellow Olive equivalents