Cultist Purple vs Medium Violet

How close are they?

ΔE 20.5, loose: different enough that you should pick on purpose. Medium Violet is noticeably darker, more saturated, warmer than Cultist Purple.

Can I use Medium Violet instead of Cultist Purple?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 20). Medium Violet is noticeably darker, more saturated, warmer than Cultist Purple.

Can I use Cultist Purple instead of Medium Violet?

The same difference applies the other way round: Cultist Purple is noticeably lighter, more muted, 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.