ΔE 17.8, loose: different enough that you should pick on purpose. Bastion Grey is a little lighter, warmer than Evergreen Fog.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 18). Bastion Grey is a little lighter, warmer than Evergreen Fog.
The same difference applies the other way round: Evergreen Fog is a little darker, 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 Evergreen Fog on the colour wheel See Bastion Grey on the colour wheel
All matches: Evergreen Fog equivalents · Bastion Grey equivalents