I like how Jay Graber (who is now CEO at Bluesky) formulated it in old blog post:

Calling a network “decentralized” only defines it by what it is not — it is not dependent on a single set of servers run by one company. What it actually is can look like many different things. Federated and peer-to-peer (p2p) protocols are different approaches to designing networks that structurally empower users.

https://medium.com/decentralized-web/decentralized-social-ne...