They all serve different purposes.

For example Mastodon is for “microblogging” or basically what you do on twitter. Everyone yelling out a few SMS messages worth of stuff and others can reply to it.

Lemmy is a “news aggregator” or basically what Reddit does. People post on a topic and others create threads of discussion on the topic.

These two services arent serving the same purposes. What they share is an underlying protocol for doing federated social networking.

I still don’t understand how I this services communicate each other. Ok, they use the same protocol, but practically how can I, on Lemmy, access content from PeerTube or Mastodon?

I’m still confused 🤔

On the fediverse, users from one instance (like me, on lemmy.nl) can talk to someone on other instance (example: lemmy.world)

Both instances have their own rules, their own communities and so on, but, we can communicate between us. I can follow a community from other instance, give likes to some other instance’s post, and so on.

BUT! It doesn’t stop there! Other services can use activity pub, too, and you can communicate with those over lemmy too!

Each service has their own thing. Like pixelfed works a bit like Instagram, or how mastodon is closer to Twitter (micro blogs). Just like we, at lemmy, are more like a reddit network.

And we can communicate with between these services! A like from mastodon can be given to a pixelfed post, for example! Or you can comment with your mastodon on a post from another service!

As far as I know, lemmy doesn’t implement cross services follow and likes (for now), but in the future you’d be able to follow people on mastodon directly from your lemmy.

So, we have: our own community (the server which you signed up), instances (other lemmy servers which we can talk to) and other services (like the ones in your picture).

Hope it helps a bit!