Editors
What an editor works with, from the backend side and from the website side: the content elements the extension adds, the profile record they render, and the editing surface a website user gets on the page itself.
Plugins
The three content elements, what each renders, and which settings each one needs.
Profile records
Creating a profile in the backend, its tabs, its child collections and its owner.
Editing in the frontend
What a website user sees on the page, and everything the editing surface can do.