Amazon Simple Notification Service (SNS) and Amazon EventBridge are both AWS services designed to handle messaging and event-driven architectures, but they serve different purposes and have distinct features. Here’s a comparison of the two:

Amazon Simple Notification Service (SNS)

Purpose

• SNS is a fully managed pub/sub (publish/subscribe) messaging service designed to send notifications to distributed systems and microservices.

Key Features

• Topics: SNS uses topics to send messages to multiple subscribers.
• Subscribers: Subscribers can be HTTP/HTTPS endpoints, AWS Lambda functions, Amazon SQS queues, email addresses, and mobile devices (via SMS and push notifications).
• Message Filtering: Allows subscribers to receive only the messages they are interested in by specifying filter policies.
• Fan-out Pattern: SNS can push messages to multiple endpoints, making it useful for sending alerts and notifications.
• High Throughput: Designed to handle high throughput and large volumes of messages.
• Durability and Reliability: Stores messages across multiple Availability Zones (AZs) to ensure durability.

Use Cases

• Sending alerts and notifications to multiple recipients.
• Decoupling microservices.
• Fan-out messages to multiple endpoints for processing.
• Mobile push notifications.

Amazon EventBridge

Purpose

• EventBridge is a serverless event bus service designed for building event-driven applications using events generated from your applications, integrated SaaS applications, and AWS services.

Key Features

• Event Buses: EventBridge uses event buses to manage events. Each AWS account has a default event bus, but you can also create custom event buses.
• Event Sources: Integrates with AWS services and third-party SaaS providers to ingest events.
• Event Rules: Allows setting up rules to filter and route events to various targets.
• Targets: Events can be routed to multiple targets such as AWS Lambda functions, Amazon SQS queues, Amazon SNS topics, Kinesis Streams, Step Functions, and more.
• Schema Registry: Automatically catalogs event schemas and allows schema discovery.
• Event Archiving and Replay: Can archive and replay events to help debug and test applications.

Use Cases

• Building event-driven architectures.
• Integrating with third-party SaaS applications to automate workflows.
• Centralized event routing within applications.
• Automating operational tasks and responding to system events.

Comparison

Feature/Aspect	SNS	EventBridge
Primary Use Case	Pub/Sub messaging and notifications	Event routing and event-driven architectures
Message Delivery	Push to subscribers	Route to multiple targets
Filtering	Subscriber-based filtering policies	Rule-based event filtering
Integration	Limited to specific protocols and endpoints	Broad integration with AWS services and SaaS applications
Event Management	Basic pub/sub model	Advanced event bus with rules, schemas, and archiving
Throughput	High throughput for notifications	Suitable for a variety of event-driven patterns
Targets	HTTP/HTTPS, Lambda, SQS, email, SMS	Lambda, SQS, SNS, Kinesis, Step Functions, etc.

Choosing Between SNS and EventBridge

• Use SNS if you need a straightforward pub/sub messaging service to send notifications or broadcast messages to multiple recipients. It’s ideal for scenarios where you need high throughput and simple message fan-out.
• Use EventBridge if you are building complex event-driven architectures and need advanced event routing capabilities, including integration with various AWS services and third-party SaaS applications. It’s suitable for applications that require sophisticated event processing, filtering, and orchestration.