1. 1. Invocation Model: AWS Lambda is an event-driven computing service that executes functions in response to events, such as changes to data in an Amazon S3 bucket or a new record being inserted into a DynamoDB table. In contrast, RabbitMQ is a message broker that allows applications to communicate by sending and receiving messages. It uses a publish-subscribe model where producers send messages to exchanges and consumers receive messages from queues created for subscriptions.

2. 2. Scaling: AWS Lambda automatically scales the execution environment to handle incoming requests. It can rapidly scale out to support a high volume of concurrent invocations, ensuring that functions are executed without the need for manual intervention. RabbitMQ, on the other hand, requires manual scaling of consumer applications to handle increased message load. It provides features like message acknowledgments and prefetch limits to control the flow of messages and avoid overwhelming consumer applications.

3. 3. Event Sources: AWS Lambda can be triggered by various event sources such as Amazon S3, Amazon DynamoDB, Amazon Kinesis, Amazon CloudWatch Events, and more. This allows developers to build serverless applications that respond to events generated by AWS services. RabbitMQ, on the other hand, is not limited to AWS services and can be integrated with any applications or systems capable of communicating over protocols like AMQP (Advanced Message Queuing Protocol).

4. 4. Execution Environment: AWS Lambda provides a fully managed execution environment for running functions, abstracting away the underlying infrastructure and operating system. Developers can focus on writing code without worrying about provisioning servers or managing resources. RabbitMQ, on the other hand, requires setting up and managing the RabbitMQ message broker infrastructure, including servers, queues, exchanges, and connections.

5. 5. Message Persistence: AWS Lambda does not provide built-in message persistence. It functions as an event-driven compute service and does not retain messages for subsequent processing by default. RabbitMQ, on the other hand, provides message persistence by storing messages in queues until they are consumed or expire. This ensures that messages are not lost in case of consumer failures or system restarts.

6. 6. Message Delivery Guarantees: AWS Lambda provides at-least-once execution semantics, meaning that functions are guaranteed to be invoked at least once, but they can be invoked multiple times in case of failures or retries. RabbitMQ provides different levels of message delivery guarantees, including at-most-once (default) and at-least-once delivery options. Developers can choose the level of reliability based on their application requirements.

In Summary, AWS Lambda and RabbitMQ differ in terms of invocation model, scaling behavior, event sources, execution environment, message persistence, and message delivery guarantees.