Developmental Editing - Concept/Idea Level.
Developmental Editing is at a level typically performed by a writing coach or writing partner. During the developmental stages, a writing coach will review and give feedback on the overall content of the material. Not all writers need Developmental Editing.
Line Editing or (structural editing) - Book/Chapter Level.
Line Editing addresses the creativity of the written material. It looks at writing style and language usage. Line Editing will adjust sentences to flow better. However, the goal of Line Editing is not to search the written material for typos, punctuation, and small errors.
Copy Editing - Sentence Level.
Copy editing is to address technical flaws rather than the creativity. It corrects grammar, punctuation, and spelling errors. It looks for consistency in spelling, hyphenations, numerals, and capitalization. Copy editing also looks for factual correctness in text which includes dates and locations. This is particularly important for non-fiction material.
Proofreading - Word Level.
Proofreading looks for - and fixes
John A. Huguley