ΔE 15.1, loose: different enough that you should pick on purpose. Grey is a little darker, much more muted than Glazier Blue.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 15). Grey is a little darker, much more muted than Glazier Blue.
The same difference applies the other way round: Glazier Blue is a little lighter, much more saturated.
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 Glazier Blue on the colour wheel See Grey on the colour wheel
All matches: Glazier Blue equivalents · Grey equivalents