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