Soul Society is an afterlife (also called the spirit world). This is also where Shinigami live and where most Souls dwell until they are reincarnated into the Human World.
Seireitei is in the center of Soul Society.
Rukongai is the largest portion of Soul Society and the most populated.
The Human World, also referred to as the World of the Living, Material World, or the Real World, is where living Humans reside.
Hueco Mundo is the dimension in which Hollow and Arrancar usually reside. It lies in between the Human World and Soul Society.