As far as I can tell from my venture into Mastodon’s feeds, the demographics of that part of Fediverse isn’t that different from what Lemmy has: the same political takes, FOSS stuff, “big corpos bad”, etc.
I wonder, is there anything that Mastodon excels at that Lemmy just doesn’t provide? For example, I noticed that there are game developers and artists posting their stuff on Mastodon. Not many game developers (or any creatives, really) on Lemmy though.
I came from Mastodon. I think Mastodon does have some good features that haven’t come to Lemmy such as account migration and bio sites verification, while Markdown and no word count limit in Lemmy excels Mastodon. Other difference are more due to the different nature of them, just like Twitter compared to Reddit, for example, more organizations, artists, developers, etc. post on Mastodon.