ΔE 16.4, loose: different enough that you should pick on purpose. Sick Green is a little darker, more saturated, cooler than Elven Green.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 16). Sick Green is a little darker, more saturated, cooler than Elven Green.
The same difference applies the other way round: Elven Green is a little lighter, more muted, 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 Elven Green on the colour wheel See Sick Green on the colour wheel
All matches: Elven Green equivalents · Sick Green equivalents