ΔE 9.2, close: similar, with a visible difference side by side. Iridescent Purple/Green is more saturated than Fairy Dust. They are different kinds of paint: Army Painter Fairy Dust is a metallic and Tamiya Iridescent Purple/Green is a pearl paint, so they won’t behave the same on the model even where the colour is close.
Usually, if you are not matching paint already on the model. Close match (ΔE 9). Iridescent Purple/Green is more saturated than Fairy Dust. They are different kinds of paint.
The same difference applies the other way round: Fairy Dust is 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 Fairy Dust on the colour wheel See Iridescent Purple/Green on the colour wheel
All matches: Fairy Dust equivalents · Iridescent Purple/Green equivalents