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