This is a definition I was redefining throughout the weekend at GenCon, and just used it to answer an e-mail to a new author. I think this is a pretty good distinction; what do you all think?
Publishing services – whether with me or someone else – means that a specific service is delivered for a specific fee. I do what you pay me for, and not any more or less. (For example, I don’t correct grammar or spelling during eBook conversion.) Someone providing publishing services gets paid by the author.
A publisher instead takes a *percentage* – usually a majority one – but handles much, if not all, of the business aspects without involving (or bothering) the author. I would hire both copy and line editor, cover artist, etc without payment from the author. The author is paid an advance against royalties (most of the time) and royalties are paid out to the author through the sale of the book to the general public. The publisher makes money from sales of the book to the public.