Genestealer Purple vs Permanent Violet Dark

How close are they?

ΔE 15.8, loose: different enough that you should pick on purpose. Permanent Violet Dark is a little darker, warmer than Genestealer Purple.

Can I use Permanent Violet Dark instead of Genestealer Purple?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 16). Permanent Violet Dark is a little darker, warmer than Genestealer Purple.

Can I use Genestealer Purple instead of Permanent Violet Dark?

The same difference applies the other way round: Genestealer Purple is a little lighter, cooler.

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.