ΔE 30.4, loose: different enough that you should pick on purpose. Indigo Sky is much more muted, cooler than Genestealer Purple.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 30). Indigo Sky is much more muted, cooler than Genestealer Purple.
The same difference applies the other way round: Genestealer Purple is much more saturated, 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 Genestealer Purple on the colour wheel See Indigo Sky on the colour wheel
All matches: Genestealer Purple equivalents · Indigo Sky equivalents