ΔE 37.7, loose: different enough that you should pick on purpose. Vicious Purple is noticeably lighter, much more saturated, warmer than Dark Blue Tone.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 38). Vicious Purple is noticeably lighter, much more saturated, warmer than Dark Blue Tone.
The same difference applies the other way round: Dark Blue Tone is noticeably darker, much 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.
See Dark Blue Tone on the colour wheel See Vicious Purple on the colour wheel
All matches: Dark Blue Tone equivalents · Vicious Purple equivalents