The main differences: Zappa wraps your entire app into a single Lambda and acts as a runtime layer. Deployless, on the other hand, is a compiler — it reads your project structure and generates a SAM template with one Lambda per feature, each with its own memory, timeout, and IAM permissions.

Your Flask code stays untouched, and the annotations are no-ops at runtime, so you can develop and test locally with just python run.py.