Editors come in various flavors, but there are three basic profiles — development, content or line, and proofreaders:
• In a nutshell, development editors scrutinize for big ticket items: character, plot, theme and transitions. They consider other aspects, too, like grammar, punctuation and spelling, but their strength is the big picture.
• Content or line editors scan for the big picture, but they're looking largely for whether the writing flows, scenes make sense and the story generally works. They also watch for grammar, punctuation and spelling.
• Proofreaders, the good ones, get out the magnifying glass. They're detail-oriented and look for errors you pray don't show up in the draft you send to your agent. Some development editors recommend using proofreaders before sending the final draft.