ΔE 25.2, loose: different enough that you should pick on purpose. Sick Green is noticeably darker, much more muted than Necrotite Green.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 25). Sick Green is noticeably darker, much more muted than Necrotite Green.
The same difference applies the other way round: Necrotite 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 Necrotite Green on the colour wheel See Sick Green on the colour wheel
All matches: Necrotite Green equivalents · Sick Green equivalents