Board Thread:Lore Discussion/@comment-72.77.73.35-20140408131341/@comment-16644430-20140428233320

Sure and despite many of them trying none of the Daedric Princes can seriously affect the mortal realm, only small scale trouble making and sponsoring some champions here and there.

I'd say it more suggests that they are roughly equals with each their own place of power, though of course the Daedra can affect their own realm a great deal more than the Aedra can theirs, but then the Oblivion planes are a lot more fluid and fickle.