The copyeditor will fix a misstated fact, spot a typo and get your prose clean.
The line editor will rearrange a paragraph and help you organize a thought more clearly.
And the editor who is your partner will tell you that the chapters are in the wrong order, that you must delete a third of what you wrote, or perhaps consider writing for TV instead. This kind of editor is the one who will tell you your time is better spent doing something else entirely.
It's easier (but not easy) to find a good copyeditor than it is to find someone generous and brave enough to help you figure out your strategy, whether you're working on a book, a career or the structure of your next project.
The copyeditor can tell you that you mangled a few facts early in your presentation. The line editor will help you untangle a complicated story near the middle. And your strategic editor will help you see that a one-on-one meeting would have been better than a presentation in the first place.
Sure, fix my typos, thanks a lot, but what's truly precious is someone able to fix your plan.
Worth noting that most critics and journalists are comfortable being metaphorical copy editors, but it's rare you find someone who speaks up with sensible thoughts about your strategy.
Treasure the folks willing and able to develop a point of view about the big picture.