ΔE 17.8, loose: different enough that you should pick on purpose. Sky Blue is a little lighter, warmer than Frost Blue.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 18). Sky Blue is a little lighter, warmer than Frost Blue.
The same difference applies the other way round: Frost 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 Frost Blue on the colour wheel See Sky Blue on the colour wheel
All matches: Frost Blue equivalents · Sky Blue equivalents