They are completely different words. Neither of them is basic vocabulary.
1) "Aren't you going to rehearse your presentation?"
"No, I know the subject. I'm prepared enough."
"I think you are too complacent."
2) "He thinks he's wonderful. He thinks he's the smartest person in the world, the most handsome person in the world, and the best dancer in the world. He's the most conceited person I've ever met."