Not the GP author, but he's talking about using 4 different AWS services in a particular architectural pattern. SNS topics give you a triggering mechanism to start the long running task. Step Functions give you light-weight flow control and state management, but don't directly perform any interesting work. Instead, the step function steps can invoke Lambda functions or jobs in Elastic Container Service to do the actual work. When they finish, the step function can move on to the next step or retry things as needed.