Dark Rust vs Earth Green

How close are they?

ΔE 7.7, close: similar, with a visible difference side by side. Earth Green is a little lighter, more muted than Dark Rust.

Can I use Earth Green instead of Dark Rust?

Usually, if you are not matching paint already on the model. Close match (ΔE 8). Earth Green is a little lighter, more muted than Dark Rust.

Can I use Dark Rust instead of Earth Green?

The same difference applies the other way round: Dark Rust is a little darker, more saturated.

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.