Substantive Editing is primarily concerned with ensuring your manuscript has the right "flow". I will challenge you to sharpen the delivery of your story and make sure it conveys precisely the tale you want it to. You have the story, I have the training; together we can make something great.
Copy Editing is the equivalent of taking your car into the shop. I'm going to strip your manuscript down to the mechanics and make sure it is running smoothly. I will fix errors (spelling, grammar, punctuation, etc.), catch inconsistencies, and remove repetition.
Proofreading is the finishing touch on a completed manuscript. I'll make sure that there are no missed pages, awkward word or page breaks, or errors in formatting. I'll do a cursory mechanical review but if I find too many errors it will need to be pushed back to the copy editing phase.