In short: centralised = 1 owner/operator, federated = many semi-autonomous operators to choose from, decentralised/distributed = everyone's an operator on the same level.
With DNS you still have groups of operators who can tell you what to do and they have the main agencies on top of that. I subscribe to the "it's not really decentralised" view.
It's not that you are not giving me source because your time is valuable and I'm dumb. It's because there is no source and these concepts don't have any standard rigorous definition.
https://www.google.com/search?q=decentralized+vs+federated
Google gives me trash. These are trash concepts, nothing written by academics or professionals or standard textbooks, or proceedings of magazines or publications.
Just blogs and cryptonerds (with different definitions).