ΔE 12.1, fair: the same colour family, but not a straight swap. Russ Grey is more saturated, warmer than Blue Gray.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 12). Russ Grey is more saturated, warmer than Blue Gray.
The same difference applies the other way round: Blue Gray is more muted, 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 Gray on the colour wheel See Russ Grey on the colour wheel
All matches: Blue Gray equivalents · Russ Grey equivalents