A Megaverse tends to contain Multiverses, some Membraneverses, Kiloverses, Megaverses, and some Hyperverses, with a Inforium in the center. It is different from a Metaverse, because a Megaverse is physical. Our megaverse is infinite.
Despite the variance of interuniversal laws and properties inside a Megaverse, they all tend to start with similar-ish kinds of matter, and tend to be bound by a few laws which are carried from the Inforium out through the Megaverse. It is a 16+2 dimensional, sometimes self-containing entity that's size can be up to zeta 0 parasecs.