ΔE 9.5, close: similar, with a visible difference side by side. Beasty Brown is a little lighter than Mushroom Brown.
Usually, if you are not matching paint already on the model. Close match (ΔE 10). Beasty Brown is a little lighter than Mushroom Brown.
The same difference applies the other way round: Mushroom Brown is a little darker.
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 Mushroom Brown on the colour wheel See Beasty Brown on the colour wheel
All matches: Mushroom Brown equivalents · Beasty Brown equivalents