ΔE 21.9, loose: different enough that you should pick on purpose. Dark Green is noticeably darker, much more muted than Green.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 22). Dark Green is noticeably darker, much more muted than Green.
The same difference applies the other way round: Green is noticeably lighter, much more saturated.
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 on the colour wheel See Dark Green on the colour wheel
All matches: Green equivalents · Dark Green equivalents