ΔE 10.5, fair: the same colour family, but not a straight swap. Autumn Sage is more muted, cooler than Green Sky.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 10). Autumn Sage is more muted, cooler than Green Sky.
The same difference applies the other way round: Green Sky is more saturated, 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 Green Sky on the colour wheel See Autumn Sage on the colour wheel
All matches: Green Sky equivalents · Autumn Sage equivalents