ΔE 7.0, close: similar, with a visible difference side by side. Flat Earth is a little lighter, warmer than Ruddy Terra.
Usually, if you are not matching paint already on the model. Close match (ΔE 7). Flat Earth is a little lighter, warmer than Ruddy Terra.
The same difference applies the other way round: Ruddy Terra is a little darker, cooler.
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 Ruddy Terra on the colour wheel See Flat Earth on the colour wheel
All matches: Ruddy Terra equivalents · Flat Earth equivalents