Night Blue vs Alaitoc Blue

How close are they?

ΔE 17.3, loose: different enough that you should pick on purpose. Alaitoc Blue is a little lighter, much more saturated, warmer than Night Blue.

Can I use Alaitoc Blue instead of Night Blue?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 17). Alaitoc Blue is a little lighter, much more saturated, warmer than Night Blue.

Can I use Night Blue instead of Alaitoc Blue?

The same difference applies the other way round: Night Blue is a little 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.