Whereas queue / message driven services (e.g. AWS SQS) are coupled with their consumers.
[1] Message queues can be a good buffer to handle spiky workloads but they have a finite capacity.
These operating overheads include: Besides reducing cost, a message queueing service seeks to simplify access to messaging resources and therefore facilitate integration efforts within organizations and between them.
A message queueing service also creates new value by providing reduced costs, enhanced performance and reliability.
In order to provide those benefits, a message queueing service leverages cloud computing resources such as storage, network, memory and processing capacity.