ΔE 8.9, close: similar, with a visible difference side by side. Monster Brown is more muted, cooler than Earth.
Usually, if you are not matching paint already on the model. Close match (ΔE 9). Monster Brown is more muted, cooler than Earth.
The same difference applies the other way round: Earth is more saturated, 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 Earth on the colour wheel See Monster Brown on the colour wheel
All matches: Earth equivalents · Monster Brown equivalents