ΔE 15.8, loose: different enough that you should pick on purpose. Park Green Flat is noticeably darker, more muted, cooler than Green FS34227.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 16). Park Green Flat is noticeably darker, more muted, cooler than Green FS34227.
The same difference applies the other way round: Green FS34227 is noticeably lighter, 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 FS34227 on the colour wheel See Park Green Flat on the colour wheel
All matches: Green FS34227 equivalents · Park Green Flat equivalents