ΔE 30.3, loose: different enough that you should pick on purpose. Beaten Purple is noticeably darker, much more saturated than Magos Purple. They are different kinds of paint: Citadel Magos Purple is a one-coat contrast-style paint and Formula P3 Beaten Purple is an opaque base/layer 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 30). Beaten Purple is noticeably darker, much more saturated than Magos Purple. They are different kinds of paint.
The same difference applies the other way round: Magos Purple 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 Magos Purple on the colour wheel See Beaten Purple on the colour wheel
All matches: Magos Purple equivalents · Beaten Purple equivalents