Are Demons and Fallen Angels the Same Spiritual Beings?

Questions about whether demons and fallen angels are the same spiritual beings (and if so, why angels don’t possess people) and why Hell wouldn’t bring Satan pleasure.

• Are demons and fallen angels the same spiritual beings, and if they’re the same, why don’t angels possess people like demons do?
• If Satan is able to able to work evil in people’s lives in Hell, wouldn’t being in Hell be something that brings him pleasure?