ΔE 11.5, fair: the same colour family, but not a straight swap. Ruddy Terra is more muted, cooler than Earth Brown.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 11). Ruddy Terra is more muted, cooler than Earth Brown.
The same difference applies the other way round: Earth Brown 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 Brown on the colour wheel See Ruddy Terra on the colour wheel
All matches: Earth Brown equivalents · Ruddy Terra equivalents