ΔE 34.0, loose: different enough that you should pick on purpose. Lucky 38 is noticeably darker, much more muted, warmer than Blue Flux.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 34). Lucky 38 is noticeably darker, much more muted, warmer than Blue Flux.
The same difference applies the other way round: Blue Flux is noticeably lighter, much more saturated, 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 Blue Flux on the colour wheel See Lucky 38 on the colour wheel
All matches: Blue Flux equivalents · Lucky 38 equivalents