ΔE 24.5, loose: different enough that you should pick on purpose. Green Sky is a little darker, much more muted, warmer than Emerald Green.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 24). Green Sky is a little darker, much more muted, warmer than Emerald Green.
The same difference applies the other way round: Emerald Green is a little 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 Emerald Green on the colour wheel See Green Sky on the colour wheel
All matches: Emerald Green equivalents · Green Sky equivalents