Someone once asked me how much time I spend editing. My response?
"How much time do I spend editing or copyediting?"
The two are different, you see. But they're commonly used interchangeably, which can cause some confusion. So here's the basic difference:
Editing refers to making changes to the content of a piece. For instance, you might reorganize, rewrite, revise, reposition -- there's a lot of "re" stuff going on. Typically, it's a very collaborative process with the writer.
Copyediting, on the other hand, involves fewer sweeping changes. It focuses more on accuracy, formatting, and sometimes (though not always) proofreading.