I was replying to a post claiming Bluesky is centralized, since it's not, really. Maybe I should have left Mastodon out of it :)

I think they're both good, but different tools for different jobs. Mastodon is good for tighter knit community. I think Bluesky has potential to be a decentralized replacement for social media with n >> dunbar's number.

The difference is in the protocol. Bluesky's atproto is IMO very clever and well designed. It's not every day I read something and think to myself, "I wish I'd thought of that!" I'd encourage anybody whose interest is piqued to dig in and read up.