This is my own personal way of seeing it, and so may be contradicted by White Wolf in the future should it pass the job along to someone else, but my take on it is as such:
I refer to the Beyond as the "conceptual without." If everything in Creation is ordered under concepts affixed to charms and assigned spirits and given values, then everything outside of Creation (which is pretty much chaos) is ordered if only by the the thoughts of one who can percieve the incomprehensible and the unknown. In that way, Oramus is similar to Jupiter in that he can see things that aren't known, but all of his knowledge applies to things outside Creation, of no practical use or sense, things which are in fact outside fate and have no value in any sort of order. When Luna brings anything from the without into Creation, she is stealing forcesdreamsfrom outside reality and melding them into the fabric of Creation to make it stronger, drawing slight similarity in this action between Luna and a fair folk. The Beyond is a place only in the sense that it is a state of mind, and the power of it as an idea is enough to stir and twist the Wyld into forms, alien vistas and terrifying monsters, as his very thoughts force the Wyld to take shape.