ΔE 8.6, close: similar, with a visible difference side by side. Light Rust is a little lighter, more saturated than Leather Brown.
Usually, if you are not matching paint already on the model. Close match (ΔE 9). Light Rust is a little lighter, more saturated than Leather Brown.
The same difference applies the other way round: Leather Brown is a little darker, more muted.
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 Leather Brown on the colour wheel See Light Rust on the colour wheel
All matches: Leather Brown equivalents · Light Rust equivalents