The Level II multiverse, is characterized by universes with different physical constants. The idea has to do with inflation and the expansion of the Universe. The Level II multiverse will be expanding, eternally, that is, forever. However, there will be some regions of space that stop stretching. These areas that have stopped stretching will form a kind of bubble, with different laws of physics. These are the different universes, each with different physical constants that govern them.
An example of bubble universes. Each with different laws of physics.