ΔE 7.8, close: similar, with a visible difference side by side. Light Rust is more muted, cooler than Catachan Flesh.
Usually, if you are not matching paint already on the model. Close match (ΔE 8). Light Rust is more muted, cooler than Catachan Flesh.
The same difference applies the other way round: Catachan Flesh is more saturated, 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 Catachan Flesh on the colour wheel See Light Rust on the colour wheel
All matches: Catachan Flesh equivalents · Light Rust equivalents