The Aurbis is the name given to the chaos, or totality, from which the cosmos was formed by Anu and Padomay. For all intents and purposes, it is the universe, encompassing the Void and all Planes of Existence including Mundus, Aetherius, and the planes of Oblivion.
Moonshadow is a realm of Oblivion created and ruled over by the Daedric Prince Azura, Queen of Dawn and Dusk.