ΔE 15.8, loose: different enough that you should pick on purpose. Sick Green is a little darker, warmer than Park Green.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 16). Sick Green is a little darker, warmer than Park Green.
The same difference applies the other way round: Park Green is a little lighter, 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 Park Green on the colour wheel See Sick Green on the colour wheel
All matches: Park Green equivalents · Sick Green equivalents