Blue Violet vs Alaitoc Blue

How close are they?

ΔE 22.3, loose: different enough that you should pick on purpose. Alaitoc Blue is a little darker, cooler than Blue Violet.

Can I use Alaitoc Blue instead of Blue Violet?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 22). Alaitoc Blue is a little darker, cooler than Blue Violet.

Can I use Blue Violet instead of Alaitoc Blue?

The same difference applies the other way round: Blue Violet is a little lighter, 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.