Aren’t copy editing and proofreading the same thing?
No. They are actually two separate tasks. A proofreader is typically the last set of eyes on a piece of work. By the time a proofreader gets a document, it should be close to publication. The proofreader will go over it thoroughly, and search for spelling mistakes, spacing issues, and grammatical errors. They will make sure that document is ready for publication.
A copy editor’s job is more involved. Copy editors will look for all the issues a proof reader does, but they will also help with sentence structure, flow and consistency. They help the author really dig in and make a piece work. Copy editors work as fact checkers. They will also look for any possible legal errors with your document.