What is the difference between a message queue and an event stream?
A queue usually distributes work among competing consumers: a worker receives or leases a message, acknowledges success, and retries failure. A stream retains an ordered event log for a retention period; consumers track offsets and independent consumer groups can replay the same events. Choose by retention, replay, ordering and consumer semantics rather than product name.
How to think about it
A queue answers who will complete this job? Competing workers receive messages, acknowledge successful work and retry failures. Standard SQS is at-least-once, so consumers must be idempotent.
A retained stream answers which consumers need this event history? Consumer groups maintain offsets and several applications can independently read or replay the same ordered events.