ΔE 11.3, fair: the same colour family, but not a straight swap. Light Magenta is a little lighter, more saturated, warmer than Fey Pink. They are different kinds of paint: Army Painter Fey Pink is an opaque base/layer paint and Golden Light 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 11). Light Magenta is a little lighter, more saturated, warmer than Fey Pink. They are different kinds of paint.
The same difference applies the other way round: Fey Pink is a little darker, 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 Fey Pink on the colour wheel See Light Magenta on the colour wheel
All matches: Fey Pink equivalents · Light Magenta equivalents