Durable Functions are not in the same category as actors. Each durable function exists to serve a single request; the model is request partitioned instead of data partitioned.

Durable Functions are great for deterministic synchronization across calls to other Azure Functions. Fan-out, fan-in, function chaining, and similar tasks are best done using Durable Functions[0].

Could you build an actor model on top of Durable Functions? Possibly. I'm not sure why you would do that, though. Azure Functions are already pretty expensive.

[0]: https://docs.microsoft.com/en-us/azure/azure-functions/durab...