ΔE 10.5, fair: the same colour family, but not a straight swap. Primary Magenta is a little lighter, more saturated than Dragon Red. They are different kinds of paint: Army Painter Dragon Red is an opaque base/layer paint and Golden Primary 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 10). Primary Magenta is a little lighter, more saturated than Dragon Red. They are different kinds of paint.
The same difference applies the other way round: Dragon Red is a little darker, 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 Dragon Red on the colour wheel See Primary Magenta on the colour wheel
All matches: Dragon Red equivalents · Primary Magenta equivalents