Amazon SQS and SNS are the two messaging standards that ensure the smooth execution of events.
Amazon SQS is a distributed message queuing service, wherein it sends messages through web applications for communications over the internet.
Amazon SNS is a managed messaging service for system-to-system and application-to-person communications.
If you are looking for sending a larger message volume to communicate with software components Amazon SQS is ideal for that.
But If you want to connect to the users directly through SMS or emails SNS should be your ideal choice.