I want to comprehend the OpenStack API, CLI, and SDK.

Are the APIs immature, crude SDKs? They are modular code specific to a language to allow for programmatic manipulation of OpenStack. What exactly is the difference from an SDK and an API for a given language?

I think of the CLI as an ad hoc API. If you use the OpenStack scripts for the CLI, you can interactively utilize OpenStack. It is an alternative from the GUI. I think of the CLI as language agnostic.

Is the Bash "API" for OpenStack the CLI?