#Mastodon is not "distributed", it's "federated". A "distributed" model only have one "database" which is copied in all nodes. In a "federated" model, there are different "databases" which communicates with each other but does not copy each other.
So, in a federated model like Mastodon and all #ActivityPub-based social networks, no one server have an exact copy of another server.
While in a distributed model like #Aether, all nodes share the same copy of everything.
🙂