What is developmental editing?
Developmental editing includes everything that touches on story or theme or other "big picture" elements. In a story, do the character actions seem compelling and is how characters speak district to each one? Is the theme clear?
For simple developmental editing, I charge 1.6 cents Canadian per word. For this I give feedback on aspects of the story, from the point of view of a careful reader, looking at many of the same elements that a reader or a scholar might when reading the text.
What is language-level editing?
Language-level editing includes anything that touches directly on the text itself, sentence by sentence, including copy editing, line editing, and proofreading. For this it is important to communicate what style you want to communicate. In a first person fictional narrative, it may be important that the narrator writes in a less formal register than a narrator who is more educated. This is part of the discussion that can also be addressed from a developmental point of view but will reflect on the level of the sentence.
What is the difference between "copy editing", "line editing" and "proofreading"?
If the individual descriptions still leave you with some uncertainty, don't worry. We usually combine more than one service into one. You can also think of them in terms of how global or local the feedback is. In order of global (or general) to local (or specific) we have: developmental editing; copy editing; line editing; proofreading. This is a generalization: clearly a comment that your character in chapter one has red hair and then is described as having blond hair in chapter 14 is specific but this is still a "higher level" than simple proofreading. In fact, proofreading would not catch that. But it would notice if the sentences with those details were poorly punctuated.