ΔE 9.6, close: similar, with a visible difference side by side. Olive Brown is a little darker, more muted than Mahogany.
Usually, if you are not matching paint already on the model. Close match (ΔE 10). Olive Brown is a little darker, more muted than Mahogany.
The same difference applies the other way round: Mahogany 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 Mahogany on the colour wheel See Olive Brown on the colour wheel
All matches: Mahogany equivalents · Olive Brown equivalents