The most common levels of editing are:
In substantive editing, a manuscript is evaluated for its core substance, its story and its style; organizational changes and large revisions may be made or suggested. Every effort is made to retain the author’s intent and voice. Sentences, paragraphs and chapters may be re-organized, or such re-organizations advised, to improve consistency of information and attain text that is smooth, flowing and clear.
Copy editing, is more technical than substantive editing. In copy editing the focus is on grammar, spelling, capitalization, punctuation and overall correctness and consistency.
Proofreading is not editing. Many people think that editing and proofreading are one and the same thing. Whenever changes have been made to a manuscript, it should be proofread to catch any minor errors, which may have been overlooked.