Some editors like to hack and slash; some offer a general tune-up to a story, others may only make a cursory run, correcting misspellings (maybe); still others don't touch a thing. I've worked with at least one example of each in my time as a writer (at least on short fiction--I hope to have the opportunity to work with one on a novel someday).
I could give these breeds of editor nicknames...The Overmind, The Mechanic, The Water-Skis, and The Open Doorway.
I've only worked with a few Overminds. Not bad experiences really, only I sometimes feel like my voice is lost to the editor's. Is that an editor's job, to rewrite my story? I don't know. I read recently that some of Raymond Carver's original manuscripts (uncovered in the last few years) were so choked by editorial comments and changes, it was almost a co-writing experience.
The Mechanics are almost always helpful, snipping unnecessary adverbs, slicing through issues of subject-verb agreement and verb tense, revving up passive language...
Water-Skis are commonplace. In today's busy world, they do the minimum to make a story work without embarrassing errors or omissions. When a story is tight, a Water-Ski has little work to do anyway. Most editors of small print/hobby press mags are doing the work as volunteers, anyway (whether they admit it or not), and have full-time employment elsewhere.
Open Doorways...well, they just let it drift in, just like the name implies.
Given the choice, I'll take a Mechanic over the rest--especially one that insists onmy approval of each change (easily done with "track changes"). A Water-Ski is appropriate at times, sure. The Overmind? Sometimes. Open Doorways...well, I hope to be finished with them (for the most part). Unless, of course, that Open Doorway leads to a spot in a pro market.
What do you expect from an editor? What do you want? What helps you to become the best writer you can be?