Begin with the stage, not the label
If chapters are still moving or the argument is changing, start by resolving those larger questions. Copyediting and proofreading do different jobs, and neither is a substitute for unfinished structural work. A final check becomes less useful if substantial rewriting follows it.
What copyediting looks for
Copyediting works through the text for grammar, punctuation, usage, consistency, and clarity within the agreed scope. An editor might make chapter titles consistent, flag a name that changes spelling, or query an unclear reference. A style sheet can record decisions about numbers, capitalization, spelling, and recurring terms.
What proofreading looks for
Proofreading is a later check, often of the typeset book. It looks for remaining errors such as a repeated word, an incorrect page reference, an uneven heading, or a typo introduced during layout. The proofreader needs the version that is actually intended for release.
A simple example
In copyediting, “The group of writers were ready” might become “The group of writers was ready,” depending on the agreed variety of English and intended meaning. In a final proof, the task might be to catch a duplicated “the” or a running header that names the wrong chapter. These are original teaching examples, not client work.
Choose a practical next step
If your draft is complete but has not had a sentence-level edit, ask about copyediting. If the text has been edited and laid out, ask about proofreading. If you are unsure, describe the work already done and provide a short representative sample. Ask the proposal to name the deliverables and the type of file you will receive.
Explore editing & proofreading or compare the proposed packages to plan the next stage.