The main difference is that workflow has state and tasks can be very long running. Also workflow can react to external asynchronous events. Visibility into over

The main difference is that workflow has state and tasks can be very long running. Also workflow can react to external asynchronous events. Visibility into overall progress is also a very important feature. When using a queueing system it is hard to answer about the current state of the business process. For example implementing service deployment to a public cloud usign Celery + RabbitMQ is very non trivial and error prone. It is a pretty streightforward Cadence workflow.