Welcome, comrade!

As another user said, it's a little different. In a nutshell, Reddit is a single big tree, all stuff within the Fediverse are more like many smaller trees.

A more nuance...

In terms of who depends on whom, imagine Reddit and its admins as a lone tree. A tree is an 'instance'. The mods are branches, and subreddits are leaves, and users as ants living on that tree.

When Reddit censors e.g. anti-fascist and pro-freedom of speech stuff, you as the ant cannot really go to another tree. Reddit isn't connected with alternatives. But the Fediverse is different.

Lemmy, Piefed, and kbin on the other hand, are more like a forest of trees. Lemmy might be the evergreens, Piefed broadleafs, mbin/kbin ferns, and so on. There isn't one "lemmy", Piefed, or mbin/kbin. There are many sidelemmies (or sidepies), which on Reddit you would call a subreddit.

There are also many trees in that forest of each type. They're connected. So when one's down, you can easily move to another tree.

Now, the Fediverse overall, is like multiple interconnected forests. There's a Peertube forest, a Friendica forest, a Lemmy/Piefed/kbin/mbin forest, and so on.

As an instance owner, you can pick your 'tree' to be (dis)connected to other trees and forests, to the extent you want, aka. (de)federation. And users can do the same.

If you're going to (self)host an instance of your own, I recommend following similar policies as the Blåhaj ones, they're good. Alternatively, donate to your instance of choice every now and then.