ΔE 51.2, loose: different enough that you should pick on purpose. Demon Blood is noticeably darker, much more muted, cooler than Fluorescent Violet.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 51). Demon Blood is noticeably darker, much more muted, cooler than Fluorescent Violet.
The same difference applies the other way round: Fluorescent Violet is noticeably lighter, much more saturated, warmer.
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 Fluorescent Violet on the colour wheel See Demon Blood on the colour wheel
All matches: Fluorescent Violet equivalents · Demon Blood equivalents