ΔE 10.0, close: similar, with a visible difference side by side. Celestial Violet is a little darker, more saturated, warmer than Iridescent Purple/Green. They are different kinds of paint: Tamiya Iridescent Purple/Green is a pearl paint and Vallejo Celestial Violet is a metallic, 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 10). Celestial Violet is a little darker, more saturated, warmer than Iridescent Purple/Green. They are different kinds of paint.
The same difference applies the other way round: Iridescent Purple/Green is a little lighter, more muted, cooler.
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 Iridescent Purple/Green on the colour wheel See Celestial Violet on the colour wheel
All matches: Iridescent Purple/Green equivalents · Celestial Violet equivalents