Individually, Amazon SQS and SNS are used for different use cases. You can, however, use them together in some scenarios.

WHEN TO USE AWS SNS

You can use SNS for a variety of purposes, including:

Sending email, SMS, and push notifications to end-users in realtime. Note that you can send push notifications to Apple, Google, Fire OS, and Windows devices.

Broadcasting messages to multiple subscribers (for example, fanning out the same push notifications to all users of your app).

Workflow systems. For example, you can use SNS to pass events between distributed apps, or to update records in various business systems (e.g., inventory changes).

Realtime alerts and monitoring applications.

WHEN TO USE AWS SQS

SQS is helpful for:

Asynchronous processing workflows.

Processing messages in parallel (by using multiple SQS queues).

Decoupling and scaling microservices, distributed systems, and serverless applications.

Sending, storing, and receiving events with reliable messaging guarantees (ordering & exactly-once processing).

https://ably.com/topic/aws-sns-vs-sqs#:~:text=SNS%20is%20typically%20used%20for,1%20minute%20to%2014%20days).