This page is still under construction.
However, for our purposes (meaning, my personal definition)…
sweeping changes to the story. Can include taking entire characters, chapters, or subplots out completely; adding more of same; switching tenses or point of view; big changes.
small changes; line edits, i.e. punctuation, spelling, grammar, layout, font, etc.
Content editing refers to the work an editor does; after her edit is complete, you the author then make revisions based on her suggestions.