ΔE 22.8, loose: different enough that you should pick on purpose. Grey Mist is noticeably darker, more muted than Pylar Glacier.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 23). Grey Mist is noticeably darker, more muted than Pylar Glacier.
The same difference applies the other way round: Pylar Glacier is noticeably lighter, 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 Pylar Glacier on the colour wheel See Grey Mist on the colour wheel
All matches: Pylar Glacier equivalents · Grey Mist equivalents