ΔE 16.9, loose: different enough that you should pick on purpose. Dark Green is a little darker, much more muted, cooler than Rocket Green.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 17). Dark Green is a little darker, much more muted, cooler than Rocket Green.
The same difference applies the other way round: Rocket Green is a little lighter, much 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 Rocket Green on the colour wheel See Dark Green on the colour wheel
All matches: Rocket Green equivalents · Dark Green equivalents