CAPABILITY_IAM - is used to create a role in Cloudformation that will be given an auto-generated role name.

CAPABILITY_NAMED_IAM - is used to create a role in Cloudformation with a custom name that you will provide.

Additional CAPABILITY_AUTO_EXPAND - is used for Cloudformation templates that have macros or nesting, It grants CloudFormation permission to automatically expand certain resources and macros, which allows for dynamic creation and management of nested stacks