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IPFS is the older system (in a good sense). It has many use cases, it’s well-documented and widely used. There are many centralized IPFS providers, and you can also use FileCoin to store your content.
Ethereum Swarm is relatively new and is under development, but it has some very exciting properties. The anonymous content storage and retrieval, the super efficient DHT management, and the strong Ethereum compatibility are unique features of this solution.