from "the street" a catamaran centerboard is commonly referred to a board that rotates up into the hull as on the Tornado, Hobie 17, or the new Nacra 5.8. A daggerboard is one that fits into to a slot in the hull and raised up through the hull.

A centerboard can have the capability of swinging back if hitting something underwater. A daggerboard does not.

A daggerboard is usually much longer and narrower than a centerboard and is a little more efficient at generating lift in the water.