Cultist Purple vs Pale Indigo

How close are they?

ΔE 18.3, loose: different enough that you should pick on purpose. Pale Indigo is a little lighter, more muted, cooler than Cultist Purple.

Can I use Pale Indigo instead of Cultist Purple?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 18). Pale Indigo is a little lighter, more muted, cooler than Cultist Purple.

Can I use Cultist Purple instead of Pale Indigo?

The same difference applies the other way round: Cultist Purple is a little darker, 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.