Brass Scorpion vs Iridescent Bronze (Fine)

How close are they?

ΔE 20.7, loose: different enough that you should pick on purpose. Iridescent Bronze (Fine) is much more muted, cooler than Brass Scorpion. They are different kinds of paint: Citadel Brass Scorpion is a metallic and Golden Iridescent Bronze (Fine) is a pearl paint, so they won’t behave the same on the model even where the colour is close.

Can I use Iridescent Bronze (Fine) instead of Brass Scorpion?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 21). Iridescent Bronze (Fine) is much more muted, cooler than Brass Scorpion. They are different kinds of paint.

Can I use Brass Scorpion instead of Iridescent Bronze (Fine)?

The same difference applies the other way round: Brass Scorpion is much more saturated, warmer.

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.