There three general types of fiberboard, all of which are made from wood fibers. Particleboard is made from small wood chips or even sawdust (particles). It has limited strength, and doesn't hold fasteners very well. The heavier "stuff" that we make speaker boxes, consoles, etc., from is MDF or medium density fiberboard. Masonite is an example of high density fiberboard. At least that's what most of the folks I know describe the stuff.