Earth 69 is a more science based reality, where there are no gods, or magic or anything paranormal. But all heroes have science related origins.
Earth-69 has significant changes to 616 such as the fact that magic does not exist. It mainly revolves around Don Blake. Also, this earth's Nick Fury is much more sinister.
Don Blake (Thor)
Luke Olsen (Loki)
Loki's Mass genocide