ΔE 10.2, fair: the same colour family, but not a straight swap. Pastel Indigo is a little lighter, more saturated, cooler than Matt Light Lilac Grey. They are different kinds of paint: AMMO by Mig Matt Light Lilac Grey is an ink, glaze or transparent paint and Army Painter Pastel Indigo is a one-coat contrast-style 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). Pastel Indigo is a little lighter, more saturated, cooler than Matt Light Lilac Grey. They are different kinds of paint.
The same difference applies the other way round: Matt Light Lilac Grey is a little darker, more muted, 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 Matt Light Lilac Grey on the colour wheel See Pastel Indigo on the colour wheel
All matches: Matt Light Lilac Grey equivalents · Pastel Indigo equivalents