Flubber Green vs Goblin Green

How close are they?

ΔE 27.2, loose: different enough that you should pick on purpose. Goblin Green is much more muted, warmer than Flubber Green.

Can I use Goblin Green instead of Flubber Green?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 27). Goblin Green is much more muted, warmer than Flubber Green.

Can I use Flubber Green instead of Goblin Green?

The same difference applies the other way round: Flubber Green is much more saturated, 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.