ΔE 22.3, loose: different enough that you should pick on purpose. Blueberry is a little lighter, more saturated, warmer than Ultramarine Blue.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 22). Blueberry is a little lighter, more saturated, warmer than Ultramarine Blue.
The same difference applies the other way round: Ultramarine 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 Ultramarine Blue on the colour wheel See Blueberry on the colour wheel
All matches: Ultramarine Blue equivalents · Blueberry equivalents