Not that I know of, but here are some between Lemmy and Mastodon:
- Upvotes in Lemmy don't translate to favorites in Mastodon
- From the Mastodon side communities are normal accounts that boost published posts.
- From Mastodon Lemmy's posts are top-level messages (i.e. not a response), and comments are responses to the original message.
- You can post to a Lemmy community from Mastodon by publishing a post and tagging the community (@community_name@server.tld)
Aren't the Olympics free?