ΔE 21.2, loose: different enough that you should pick on purpose. Iridescent Silver (Fine) is noticeably lighter than Iron Hands Steel. They are different kinds of paint: Citadel Iron Hands Steel is a metallic and Golden Iridescent Silver (Fine) is a pearl paint, 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 21). Iridescent Silver (Fine) is noticeably lighter than Iron Hands Steel. They are different kinds of paint.
The same difference applies the other way round: Iron Hands Steel is noticeably darker.
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 Iron Hands Steel on the colour wheel See Iridescent Silver (Fine) on the colour wheel
All matches: Iron Hands Steel equivalents · Iridescent Silver (Fine) equivalents