ΔE 12.3, fair: the same colour family, but not a straight swap. Medium Violet is a little lighter, more saturated than Purple Tone. They are different kinds of paint: Army Painter Purple Tone is a wash/shade and Golden Medium Violet is an opaque base/layer 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). Medium Violet is a little lighter, more saturated than Purple Tone. They are different kinds of paint.
The same difference applies the other way round: Purple Tone 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 Purple Tone on the colour wheel See Medium Violet on the colour wheel
All matches: Purple Tone equivalents · Medium Violet equivalents