ΔE 16.5, loose: different enough that you should pick on purpose. Iridescent Copper Light (Fine) is noticeably darker, more muted than Screaming Bell. They are different kinds of paint: Citadel Screaming Bell is a metallic and Golden Iridescent Copper Light (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 17). Iridescent Copper Light (Fine) is noticeably darker, more muted than Screaming Bell. They are different kinds of paint.
The same difference applies the other way round: Screaming Bell 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 Screaming Bell on the colour wheel See Iridescent Copper Light (Fine) on the colour wheel
All matches: Screaming Bell equivalents · Iridescent Copper Light (Fine) equivalents