ΔE 37.4, loose: different enough that you should pick on purpose. Space Grey is noticeably darker, much more muted, warmer than Blue Glacier.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 37). Space Grey is noticeably darker, much more muted, warmer than Blue Glacier.
The same difference applies the other way round: Blue Glacier is noticeably lighter, much 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 Blue Glacier on the colour wheel See Space Grey on the colour wheel
All matches: Blue Glacier equivalents · Space Grey equivalents