Both EventBridge and SNS can be used to develop event-driven applications, and your choice will depend on your specific needs.
Amazon EventBridge is recommended when you want to build an application that reacts to events from your own applications, SaaS applications, and AWS services. EventBridge is the only event-based service that integrates directly with third-party SaaS partners. EventBridge also automatically ingests events from over 200 AWS services without requiring developers to create any resources in their account.
EventBridge uses a defined JSON-based structure for events, and helps you create rules that are applied across the entire event body to select events to forward to a target. EventBridge currently supports over 20 AWS services as targets, including Lambda, SQS, SNS, and Amazon Kinesis Data Streams, and Data Firehose.
Amazon SNS is recommended for applications that need high fan out (thousands or millions of endpoints). A common pattern that we see is that customers use SNS as a target for their rule to filter the events that they need and fan out to multiple endpoints.
Messages are unstructured and can be in any format. SNS supports forwarding messages to six different types of targets, including Lambda, SQS, HTTP/S endpoints, SMS, mobile push, and email. Amazon SNS typical latency is under 30 milliseconds. A wide range of AWS services send SNS messages by configuring the service to do so (more than 30, including Amazon EC2, Amazon S3, and Amazon RDS).