What is a Polyhedral wing? And what is the difference between a Polyhedral wing and a normal wing?

A regular wing has dihedral-the left panel is straight,as is the right panel, and there is a joint in the middleto establish the dihedral angle. A polyhedral wing has another joint in each wing panel, so there are several dihedral angles.

Lots of model sailplanes have polyhedral wings. Technically, the Corsair would have a polyhedral wing. Even the new huge airbus 380 has a polyhedral wing. But mostly wings that are called polyhedral have conventional dihedral in the center joint and then the tip panes are upswept even more. Take a look at a Goldberg Gentle Lady or a Craft Air Butterfly.

"Di" as in Dihedral means two as in the two angles of the standard wings. When the airplane is sitting level. Each wing is angled up. There are "di" (two) angles.

"Poly" means many. More than two. It could be 3 or mor angles. And they don't always have to be in the same direction like on the Corsair.

By the way, the Corsair has a shape that is known as an "Inverted Gull" wing.