Hello from Piefed! I was a regular on Lemmy and Mastodon for years, but I migrated to Piefed because it is much more lightweight.
The features page shows some differences between Piefed and Lemmy - https://join.piefed.social/features/ Mostly, I appreciate that it is written in Python, so more developers in the community may easily understand and contribute to the code base, and that it is so lightweight. When I connect to the internet I always have to consider data caps, so it's a relief when websites make a genuine effort to be efficient. I can reliably browse the fediverse through Piefed even when my access is throttled to 50Kbps download.