Cobalt Violet Hue vs Witch Purple

How close are they?

ΔE 29.7, loose: different enough that you should pick on purpose. Witch Purple is noticeably lighter, much more saturated than Cobalt Violet Hue.

Can I use Witch Purple instead of Cobalt Violet Hue?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 30). Witch Purple is noticeably lighter, much more saturated than Cobalt Violet Hue.

Can I use Cobalt Violet Hue instead of Witch Purple?

The same difference applies the other way round: Cobalt Violet Hue is noticeably darker, much more muted.

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.