ΔE 11.1, fair: the same colour family, but not a straight swap. Ultramarine Blue is a little lighter, more saturated, warmer than Alaitoc Blue.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 11). Ultramarine Blue is a little lighter, more saturated, warmer than Alaitoc Blue.
The same difference applies the other way round: Alaitoc Blue is a little darker, 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.
See Alaitoc Blue on the colour wheel See Ultramarine Blue on the colour wheel
All matches: Alaitoc Blue equivalents · Ultramarine Blue equivalents