Purple Tone vs Vicious Purple

How close are they?

ΔE 29.9, loose: different enough that you should pick on purpose. Vicious Purple is noticeably lighter, more muted than Purple Tone.

Can I use Vicious Purple instead of Purple Tone?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 30). Vicious Purple is noticeably lighter, more muted than Purple Tone.

Can I use Purple Tone instead of Vicious Purple?

The same difference applies the other way round: Purple Tone is noticeably darker, more saturated.

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.