Belos views himself as a hero but Adam does things for fun without any care in the world. He is just a frat boy.

They don't have nothing in common, but they aren't similar.

What?

The only two options are they have so much in common, or they have nothing in common. There's no in-between. What I'm saying is, sure, they have some minor similarities, but not enough to say that they have a lot in common.

They both commit genocide, they both wear cool scary masks, they've both lived for many years and they both received undignified deaths. Though Adam isn't pure evil like Emperor Belos. Adam has redeeming qualities. He gave a warm and reassuring smile to Lute before he succumbed to his mortal wounds.

Yes, they have minor similarities. That "they both lived for many years" one though doesn't count though, as Belos was around for roughly 350 years and Adam was as old as the earth.

They also are very different though. Belos kills because of his desperate need to be the hero combined with his both fear and disgust of witches, while Adam kills sinners purely for entertainment. Belos is a master manipulator, but Adam was always truthful about his intentions. Belos cares about no one but himself, but Adam does care about people like Lute and other angels.