SNS is a push mechanism, as supposed to be SQS which is pull mechanism.
It pushes cloud notification directly to the mobile devices.
SNS can deliver the message via SMS/Email to SQS or any HTTP end point.
To avoid message loss, message published in the SNS are stored redundantly across multiple availability zone.
SNS Topic
SNS allows to group multiple recipients using the topics. A topic is an access point for allowing recipients to dynamically subscribe for identical copies of the same notification.
One topic can support deliveries to multiple end point types – e.g. you can group together iOS, Android and SMS recipients.
SNS Benefits
Instantaneous push based delivery (no Pulling)
Simple API and easy integration with applications.
Flexible message delivery over multiple transport protocol.
Inexpensive, pay-as-you-go model with no up-front costs
Web-based AWS management console offers simplicity of a point-and-click interface.
SNS vs SQS
Both are messaging services in AWS.
SNS is Push
SQS is Pull
SNS Pricing
$0.50 per 1 million SNS Requests.
$0.06 per 100000 Notification deliveries over HTTP.
$0.75 per 100 notifications delivered over SMS.
$2.00 per 100000 notifications delivered over email.