AWS Step Functions come in two flavours: Standard and Express. They share a definition language called ASL, but a lot of the API operations are not supported across both types. I didn’t find a good side-by-side comparison showing the support for each individual API operation, so I made one. This could help you decide if your Standard workflows could be replaced by Express workflows.
There is a good side-by-side comparison for an overview of the two types of workflow. Understanding those differences helps to explain why certain operations are not supported.
Graham "Grundlefleck" Allan is a Software Developer living in Scotland. His only credentials as an authority on software are that he has a beard. Most of the time.