PieFed is written in Python, and so has already managed to surpass Lemmy in available features (by a lot, and new ones continue to be added practically weekly), despite Lemmy having an enormous head start. Lemmy is written in Rust and even high experienced and capable C++ developers do not know how to work with it, plus the language itself is not finished.

Tbh, there are still some things that Lemmy does better, like having a post + comment preview, and Lemmy has a really excellent search feature (though you don't even need an account to use that...). However, PieFed will continue to run laps around Lemmy for the foreseeable future, as feature requests languish for literally many years (not joking here) in Lemmy, but people are willing (and capable) to volunteer and they show up in PieFed quickly.

The best way to learn about PieFed, as you already saw, is just to go check it out, but be prepared to fall in love instantly, bc those features are truly amazing! 😍🤩

Edit: e.g. https://piefed.social/ .