ΔE 10.0, close: similar, with a visible difference side by side. Light Rust is a little lighter, cooler than Earth Clay.
Usually, if you are not matching paint already on the model. Close match (ΔE 10). Light Rust is a little lighter, cooler than Earth Clay.
The same difference applies the other way round: Earth Clay is a little darker, 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 Clay on the colour wheel See Light Rust on the colour wheel
All matches: Earth Clay equivalents · Light Rust equivalents