Editing includes proofreading and might involve making changes to a text, its style (diction and syntax), structure, its cohesion, to list a few. Editing may require the writer to make some major changes to the text or to simply correct a few mistakes.
Nonfiction: There are many forms of nonfiction: journalism, creative nonfiction (fiction techniques: metaphors and dialogue), content on web pages, advertising, blogging, memoirs, academic, and personal essays, to list just a few. All of them must be held together by a central idea, often called the controlling idea, or, in academic writing, the thesis statement. The reader is investing time and must know where the writing is leading.