Dark Sky vs Von Evile Purple

How close are they?

ΔE 18.4, loose: different enough that you should pick on purpose. Von Evile Purple is noticeably darker, warmer than Dark Sky.

Can I use Von Evile Purple instead of Dark Sky?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 18). Von Evile Purple is noticeably darker, warmer than Dark Sky.

Can I use Dark Sky instead of Von Evile Purple?

The same difference applies the other way round: Dark Sky is noticeably 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.