ΔE 11.5, fair: the same colour family, but not a straight swap. Quinacridone Magenta is more muted, cooler than Warlock Purple. They are different kinds of paint: Army Painter Warlock Purple is an opaque base/layer paint and Golden Quinacridone Magenta is an ink, glaze or transparent paint, so they won’t behave the same on the model even where the colour is close.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 12). Quinacridone Magenta is more muted, cooler than Warlock Purple. They are different kinds of paint.
The same difference applies the other way round: Warlock Purple is 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.
See Warlock Purple on the colour wheel See Quinacridone Magenta on the colour wheel
All matches: Warlock Purple equivalents · Quinacridone Magenta equivalents