A network is called decentralized when it doesn’t depend on a single entity, and thus does not pass through a central server where all of the resources are stored. A decentralized system gives the possibility to third parties to set up a server for a service and to transmit its data.
A distributed network does not rely on any server. It’s a P2P system. Peers who communicate with each other and exchange data over the network.
To learn more on the topic you can read the dedicated blogpost:
Centralized vs Decentralized vs Distributed Systems
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