Higher being

I was in a discussion where part of the topic came to talk about gods, I'm a little confused if gods and demons are different beings and there isn't much of a definition for demons to be higher entities like gods, (I noticed this in Glory's story she dominated an infernal dimension) so the ancients or higher demons didn't have powers like those of a god? Because I believed it was the same definition of power.

Would a witch full of dark magic have enough power to harm Glory? I remembered some episodes from season 5 where Glory and Willow fight, and also when Dark Willow was already full of dark magic fighting Buffy and I found it quite interesting, or even vampires? Could a witch in the Dark Willow state with all that dark magic and rage harm beings as powerful as a God like Glory? Or did Dark Willow just assume the proportions it did because of the script?