ΔE 19.6, loose: different enough that you should pick on purpose. Sick Green is noticeably darker, cooler than Spring Green.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 20). Sick Green is noticeably darker, cooler than Spring Green.
The same difference applies the other way round: Spring Green is noticeably lighter, 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 Spring Green on the colour wheel See Sick Green on the colour wheel
All matches: Spring Green equivalents · Sick Green equivalents