ΔE 8.1, close: similar, with a visible difference side by side. Rust is cooler than Steel Legion Drab. They are different kinds of paint: Citadel Steel Legion Drab is an opaque base/layer paint and Vallejo Rust is a fluorescent or effect paint, so they won’t behave the same on the model even where the colour is close.
Usually, if you are not matching paint already on the model. Close match (ΔE 8). Rust is cooler than Steel Legion Drab. They are different kinds of paint.
The same difference applies the other way round: Steel Legion Drab is 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 Steel Legion Drab on the colour wheel See Rust on the colour wheel
All matches: Steel Legion Drab equivalents · Rust equivalents