Unlike most other basic “proofreading” packages, ours includes copy-editing where needed, light revision, rewriting and improved word choice, as well as a one page summary of some big picture issues that can be improved. If we see something that looks bad, we’ll fix it – but we won’t wrack our brains trying to solve bigger issues like plotting, character motivation, story architecture, etc.
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.