Polishing
Polishing is a service specifically designed for authors who are preparing to send their manuscript out to agents or publishing houses or who are going to be self-publishing. It includes proofreading for typos, spelling errors, punctuation errors, internal consistency problems, misused words, and grammatical errors. Additionally, I reformat the manuscript into standard format for submission. I do this service in MS Word, using the "comments" and "track changes" feature, for easy viewing of corrections.
Note that I try to have a very light hand, so as not to interfere with an author's voice and style -- but I am always willing to polish a manuscript using a heavier hand, to help authors improve sentence flow and word choice.
Developmental Editing.
I use "developmental editing" as a catchall term for what people refer to as line editing, stylistic editing, substantive editing, and/or critique. I go line by line through the manuscript to clarify meaning, polish language, and help the author organize both their own ideas and the structure of the complete work. I include comments throughout the manuscript or in a 3 - 5 page "editorial letter" on plot, characterization, character development, story idea, and writing style. And, of course, once the editing and critique is complete, I am always available to my clients to answer their questions and help tease out new ideas.
Copyediting and Proofreading.
These are specific terms in the publishing industry used to refer to very specific services. I do offer these services. Copyediting is what publishers do to manuscripts before they are typeset -- it includes editing for grammar, usage, spelling, punctuation, consistency, and mechanics of style, but it also involves writing up a style sheet and marking the manuscript for the typesetter. Most authors do not need this until their manuscripts are ready to be typeset; if you are preparing to self-publish or looking for an edge on your competition when you submit, I recommend my polishing service instead.
Proofreading is the reading of the proofs -- this happens after the manuscript is typeset, to make sure no errors snuck in. Some published authors prefer to have someone else do the proofreading, since they are too close to the text to catch errors, and most publishing companies hire freelancers (like me!) rather than keep people in-house to proofread. But, again, if you are preparing to self-publish or looking for an edge on your competition when you submit, I recommend my polishing service instead.