They are really quite interchangeable as far as their result goes, and it's mostly a flavour thing regarding the action and description. In my head, Awareness can be used for a more general awareness of your surroundings and situation, while Notice is about spotting odd details that stand out.
Or if you want a more technical definition, Awareness is a "save" roll that the GM can call for when the PCs are heading for a disaster ("So you just wander into the tomb? Ok, anyone got Awareness?") and Notice is a "move" roll that the players can call for when they want more information ("Do I notice anything strange about him as he says that? Is he lying?"). If that distinction doesn't make sense, you can conflate the two without any complications.