What is the difference between a hexomino and an octacube?

Answer 1

Not much similarity. Hexomino is any 6 squares attached to each other by at least one edge for every pair of squares. It's in 2 dimensions, in a plane.

Octacube is in 4 dimensions, which we have trouble visualizing. There's a sculpture of it in a math department in Pennsylvania. There is no corresponding 3 dimensional solid. The octacube has 24 cells.