on Mastodon, you live on instances.
the minute you open an account, say disturbia@abc.com.
you are bound to the rules of the abc.com server. they are your lord. they tell you what you can and what you cannot say, how much text you can write, what kind of media you can or cannot upload, and if let say they choose to close your account, you got zero rights to that account. no legal repercussion whatsoever.
on Nostr, the server doesnt own you. you can create bilateral mutual agreement with how many servers you like. you own your own nsec and npub. and if you hate one server or the server hates you, you can simply remove it and add a new one.
that..my friend is the real definition of social media freedom.