ΔE 16.1, loose: different enough that you should pick on purpose. Steel Grey is noticeably darker, cooler than Glazier Blue.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 16). Steel Grey is noticeably darker, cooler than Glazier Blue.
The same difference applies the other way round: Glazier Blue is noticeably lighter, 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 Glazier Blue on the colour wheel See Steel Grey on the colour wheel
All matches: Glazier Blue equivalents · Steel Grey equivalents