“Editing” deals with things like continuity, whether certain elements should be moved, removed or added in order to enhance the flow or clarify aspects of the writing.
Copyediting looks at punctuation, grammar, word use and spelling.
An editor examines the overall picture and helps the writer craft interesting characters, a good plot, and elements that will gratify the reader. Editors will often question the necessity of certain scenes or the actions of certain characters. They serve as guides on the road to making the writing great.
Copyeditors don’t advise on story direction or any other such elements of a book. Their job is to ensure that punctuation, grammar, and spelling are all correct.