ΔE 22.0, loose: different enough that you should pick on purpose. Troll Snot Green is noticeably lighter than Elysian Green.
Can I use Troll Snot Green instead of Elysian Green?
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 22). Troll Snot Green is noticeably lighter than Elysian Green.
Can I use Elysian Green instead of Troll Snot Green?
The same difference applies the other way round: Elysian Green is noticeably darker.
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.