ΔE 26.7, loose: different enough that you should pick on purpose. Wurm Green is noticeably darker, cooler than Poisonous Cloud.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 27). Wurm Green is noticeably darker, cooler than Poisonous Cloud.
The same difference applies the other way round: Poisonous Cloud 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 Poisonous Cloud on the colour wheel See Wurm Green on the colour wheel
All matches: Poisonous Cloud equivalents · Wurm Green equivalents