RabbitMQ difference between expires and auto-delete?

Question

The "RabbitMQ in Action" book on page 19 gives these descriptions of exclusive and auto-delete:

auto-delete - The queue is automatically deleted when the last consumer unsubscribes. If you need a temporary queue used only by one consumer, combine auto-delete with exclusive. When the consumer disconnects, the queue will be removed.

Then, in https://www.rabbitmq.com/ttl.html, gives expeire description:

expires policy controls for how long a queue can be unused before it is automatically deleted. Unused means the queue has no consumers, the queue has not been recently redeclared (redeclaring renews the lease),and basic.get has not been invoked for a duration of at least the expiration period

Answer 1

The plain and simple answer here is that exclusive/auto-delete will delete the queue immediately after the first consumer has disconnected, while expires will delete the queue after a period of inactivity regardless of consumer(s) having connected to it in the past.

Answer 2

expalation for auto-delete: the queue is deleted when all consumers have finished using it. The last consumer can be cancelled either explicitly or because its channel is closed. If there was no consumer ever on the queue, it won't be deleted. Applications can explicitly delete auto-delete queues using the Delete method.

explanation for expires: Expiry time can be set for a given queue by setting the x-expires argument to queue.declare, or by setting the expires policy. This controls for how long a queue can be unused before it is automatically deleted. Unused means the queue has no consumers, the queue has not been recently redeclared (redeclaring renews the lease), and basic.get has not been invoked for a duration of at least the expiration period. This can be used, for example, for RPC-style reply queues, where many queues can be created which may never be drained.

I think it would be better to use expires instead of auto-delete because if somehting happens and the subscriber went down for a short time then the msg will not be lost that's a big advantage of using expires and that explains simply the difference between the two.