ΔE 12.7, fair: the same colour family, but not a straight swap. Earth is more saturated, cooler than Rust Ochre.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 13). Earth is more saturated, cooler than Rust Ochre.
The same difference applies the other way round: Rust Ochre 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 Rust Ochre on the colour wheel See Earth on the colour wheel
All matches: Rust Ochre equivalents · Earth equivalents