ΔE 64.5, loose: different enough that you should pick on purpose. Fluorescent Blue is noticeably darker, much more saturated than Brilli White.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 65). Fluorescent Blue is noticeably darker, much more saturated than Brilli White.
The same difference applies the other way round: Brilli White is noticeably lighter, 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.
See Brilli White on the colour wheel See Fluorescent Blue on the colour wheel
All matches: Brilli White equivalents · Fluorescent Blue equivalents