Bronze Shadow vs Ryza Rust

How close are they?

ΔE 9.1, close: similar, with a visible difference side by side. Ryza Rust is a little darker than Bronze Shadow.

Can I use Ryza Rust instead of Bronze Shadow?

Usually, if you are not matching paint already on the model. Close match (ΔE 9). Ryza Rust is a little darker than Bronze Shadow.

Can I use Bronze Shadow instead of Ryza Rust?

The same difference applies the other way round: Bronze Shadow is a little lighter.

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.