ΔE 5.1, very close: most people won’t see a difference side by side. Burnt Sienna is more saturated than Rust. They are different kinds of paint: Army Painter Rust is an opaque base/layer paint and Golden Burnt Sienna is an ink, glaze or transparent paint, so they won’t behave the same on the model even where the colour is close.
Yes, for most jobs. Very close match (ΔE 5). Burnt Sienna is more saturated than Rust. They are different kinds of paint.
The same difference applies the other way round: Rust is 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 Rust on the colour wheel See Burnt Sienna on the colour wheel
All matches: Rust equivalents · Burnt Sienna equivalents