ΔE 54.4, loose: different enough that you should pick on purpose. Copper is noticeably darker, much more saturated than Iron Hue.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 54). Copper is noticeably darker, much more saturated than Iron Hue.
The same difference applies the other way round: Iron Hue 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 Hue on the colour wheel See Copper on the colour wheel
All matches: Iron Hue equivalents · Copper equivalents