ΔE 48.3, loose: different enough that you should pick on purpose. Pearl Blue is noticeably darker, much more saturated than Iron Hands Steel. They are different kinds of paint: Citadel Iron Hands Steel is a metallic and Tamiya Pearl Blue 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 48). Pearl Blue is noticeably darker, much more saturated than Iron Hands Steel. They are different kinds of paint.
The same difference applies the other way round: Iron Hands Steel is noticeably lighter, much 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 Iron Hands Steel on the colour wheel See Pearl Blue on the colour wheel
All matches: Iron Hands Steel equivalents · Pearl Blue equivalents