Proofreading is intended to pick up the final typos and spelling mistakes and to correct inconsistencies, like making sure the word “proofreading” is always spelled as one word and not “proof-reading” or “proof reading.”

Copy editing checks for typos and spelling errors along with correcting grammar, language, and syntax errors. I will also pay attention to punctuation such as commas, semicolons, and quotation marks.

Line editing is a more intensive structural edit that focuses on the finer aspects of language – the flow of ideas, transition elements, tone, and style. I'll suggest changes to make sentences crisper and tighter by fixing redundancy and verbosity issues, while improving awkward sentence and paragraph construction without a full rewrite.

Development editing means the book gets a full, substantial, structural, developmental edit. This will often include everything that’s involved in proofreading and copy-editing, plus a detailed critique of the essential
elements of the story (in the case of a novel), which include:

Setting

Timeline

Characterization

Plot

Story structure

Pacing

Presentation

Marketability