@Miredly @ramgarlic
I would add:
- Decentralized: Like email, you can use a diferent instance (server) than any other person, and still be in contact with them
- Federated: Diferent services talk to each other. i.e. you can follow from your Mastodon people in Pixelfeld

Decentralization is important, if your instance change and you don´t like it, you can flight to another instance

Federation has some limits. I.e. only if your post contains an image will be seen from a follower in Pixelfeld.