ΔE 8.1, close: similar, with a visible difference side by side. Flat Brown is more saturated, cooler than Ashroot.
Usually, if you are not matching paint already on the model. Close match (ΔE 8). Flat Brown is more saturated, cooler than Ashroot.
The same difference applies the other way round: Ashroot is 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 Ashroot on the colour wheel See Flat Brown on the colour wheel
All matches: Ashroot equivalents · Flat Brown equivalents