ΔE 16.4, loose: different enough that you should pick on purpose. Rusty Metal is noticeably darker, more muted than Iridescent Gold Deep (Fine). They are different kinds of paint: Golden Iridescent Gold Deep (Fine) is a pearl paint and Vallejo Rusty Metal is a metallic, so they won’t behave the same on the model even where the colour is close.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 16). Rusty Metal is noticeably darker, more muted than Iridescent Gold Deep (Fine). They are different kinds of paint.
The same difference applies the other way round: Iridescent Gold Deep (Fine) is noticeably lighter, more saturated.
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 Iridescent Gold Deep (Fine) on the colour wheel See Rusty Metal on the colour wheel
All matches: Iridescent Gold Deep (Fine) equivalents · Rusty Metal equivalents