Board Thread:The Flash discussions/@comment-9346948-20181205013242/@comment-24152851-20181208072006

Well Manhattan was exploring a very different idea. With Superman he was a god trying to live as a human. While with Manhattan he was a god hailed as a god who could never live a normal life as he got more and more detacched, with that eventually accumulating in the question "what happens when God stops caring about what happens to the people?"

Plus despite how invincible Superman is, he can be defeated. Whereas Manhattan cannot be beaten in any respect, he is the absolute top of the power food chain and his story is about where does he go from there.