ΔE 17.0, loose: different enough that you should pick on purpose. Green Sky is noticeably darker, more saturated, warmer than Faded Green.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 17). Green Sky is noticeably darker, more saturated, warmer than Faded Green.
The same difference applies the other way round: Faded Green is noticeably lighter, 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 Faded Green on the colour wheel See Green Sky on the colour wheel
All matches: Faded Green equivalents · Green Sky equivalents