ΔE 17.2, loose: different enough that you should pick on purpose. Deep Sky Blue is noticeably darker, more muted, warmer than Light Blue.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 17). Deep Sky Blue is noticeably darker, more muted, warmer than Light Blue.
The same difference applies the other way round: Light Blue is noticeably lighter, more saturated, 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 Light Blue on the colour wheel See Deep Sky Blue on the colour wheel
All matches: Light Blue equivalents · Deep Sky Blue equivalents