ΔE 18.4, loose: different enough that you should pick on purpose. Light Violet is a little lighter, warmer than Deep Cobalt Blue.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 18). Light Violet is a little lighter, warmer than Deep Cobalt Blue.
The same difference applies the other way round: Deep Cobalt Blue is a little darker, 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 Deep Cobalt Blue on the colour wheel See Light Violet on the colour wheel
All matches: Deep Cobalt Blue equivalents · Light Violet equivalents