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