ΔE 10.9, fair: the same colour family, but not a straight swap. Dechala Lilac is a little lighter, cooler than Violet. They are different kinds of paint: AMMO by Mig Violet is an ink, glaze or transparent paint and Citadel Dechala Lilac 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 11). Dechala Lilac is a little lighter, cooler than Violet. They are different kinds of paint.
The same difference applies the other way round: Violet is a little darker, 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 Violet on the colour wheel See Dechala Lilac on the colour wheel
All matches: Violet equivalents · Dechala Lilac equivalents