Copyediting goes a level deeper than proofreading to also look at sentence structure, best word choice, awkward phrasing, word/phrase repetition, minor fact checking, and formatting. The main concern here is to improve the overall flow of the telling of your story. Things like ambiguous sentences and repetitive word choice can take your reader out of the story, which limits their connection to the plot, characters, the message you are trying to communicate, and to you as the author.
For you to get a better feel of the level of editing involved in copyediting, I am willing to do a sample copyedit of the first 1,000 words of your manuscript for $10 (for manuscripts over 7,000 words).
For pricing information, please see Pricing & Payment.