There seems to be something half-way between beta-reading and development editing. I think it’s right for many new writers — I’m just finishing my first book, and was not about to pay a real development editor, but beta readers weren’t engaged enough (especially friends unwilling to point out the negatives). But it this kind of editing doesn’t really have a clear name.
You might hire someone for a proofread, but let the editor know that you’re open to hearing from him or her if the work needs a heavier edit. The editor would need to present you with evidence in the form of sample pages that showcase what’s needed—and your job is to make sure you agree. You want to feel like an editor’s edits are polishing your work and making it shine. If you feel dread or anger, or even if you feel misunderstood, it’s likely not a good fit. At the very least you want to share your reactions with the editor so they can respond or change course.
I got in touch with Ebook Launch lately to sort out a cover for my second book, and I cannot recommend them enough. The process was quick and easy, and the effort put into capturing the mood of my story was apparent from the first sketch. Their service was friendly and accommodating, and they were open to making or reverting changes to my covers without any trouble. I appreciate the hard work they put in on my behalf, and wholly recommend their services.
Obviously there is a big difference. I actually started with screenplays (with some mild success) partly due to hearing that as long as you have a good story, the grammatical errors won’t be a big deal. Well, that was not true. Maybe if a producer liked the story or I was already established but every contest I entered always came back with feedback about the grammatical errors. Even if I won or placed as a finalist, I always received critique on that. Very little is spelling error, it was more about structure, etc.