ΔE 18.2, loose: different enough that you should pick on purpose. Foul Green is a little darker, cooler than Elixir Green.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 18). Foul Green is a little darker, cooler than Elixir Green.
The same difference applies the other way round: Elixir Green is a little 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 Elixir Green on the colour wheel See Foul Green on the colour wheel
All matches: Elixir Green equivalents · Foul Green equivalents