(Vastly different) in scale, but not category.

1. The fediverse simply doesn't have the infrastructure (centralization) to support a person or group of people from despotically lording over the only community for a topic. On Reddit, there's only one /r/cars. You can't start a other-reddit.com/r/cars.

2. Fediverse admins (allegedly) can and do oust moderators that went sour and replace them. Reddit only does that when advertiser dollars are directly in jeopardy (crime, bigotry subreddits, protests of Reddit changes, etc.)

So while tyrants can and do pop up on Lemmy, people can and do simply stop visiting their communities. You can't really do that on Reddit other than making an /r/cars2 and get a trickle of traffic compared to /r/cars no matter how well you run /r/cars2 compared to /r/cars.