Yes that's fair to say for sure. Pleroma is also ActivityPub based but Pleroma users tend to be more chill while a lot of Mastodon users are Tumblr grade SJWs. As you can imagine many Mastodon admins ban Pleroma instances just because they use Pleroma.

But the big difference is that the client and relay are combined in the ActivityPub model regardless of what platform you use. You can cheaply self host Pleroma (Mastodon is very resource intensive) but running an open Nostr relay is as cheap and contributes more meaningfully to a decentralised protocol.

I've used both extensively (ActivityPub and Nostr) and by far Nostr is superior.