If you're dealing purely with web requests, then yeah, API Gateway + Lambda sounds pretty similar to a Django function. But having used both, it's a lot easier and faster to setup API GW and Lambda than it is a Django app.
And if you're not dealing with purely web requests, then they're very different. Most of my lambdas trigger off of Kinesis, SNS, and SQS events. Work gets sent to these queues/notification endpoints, and then the Lambda function does work based off the data received there, and scales to handle the amount of data automatically.
And if you're not dealing with purely web requests, then they're very different. Most of my lambdas trigger off of Kinesis, SNS, and SQS events. Work gets sent to these queues/notification endpoints, and then the Lambda function does work based off the data received there, and scales to handle the amount of data automatically.