ΔE 18.7, loose: different enough that you should pick on purpose. Light Sea Blue is a little darker, much more saturated, cooler than Grey-Blue.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 19). Light Sea Blue is a little darker, much more saturated, cooler than Grey-Blue.
The same difference applies the other way round: Grey-Blue is a little lighter, much more muted, warmer.
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 Grey-Blue on the colour wheel See Light Sea Blue on the colour wheel
All matches: Grey-Blue equivalents · Light Sea Blue equivalents