Line editing and copyediting overlap somewhat, and line editors often catch mechanical errors in passing. Yet these two types of editing are meaningfully different. Consider these examples:
Original sentences: Another tourist attraction in Hamburg is the opportunity to eat a Sunday morning breakfast consisting of a fish sandwich and coffee. Its literally a must at the Fishmarkt (fish market) in this port on the North Sea.
A line editor’s first concern would be to trim and power up these sentences, starting by replacing is with an active verb. One possible first opening: On Sunday mornings, tourists in Hamburg can breakfast on a fish sandwich and coffee. Other stylistic changes would surely include omitting the word literally, which adds nothing to the meaning. A line editor might also point out that, although Hamburg is a port, it’s not on the North Sea but rather connected to the North Sea by the Elbe River.
A copyeditor would zoom in on Its (correctly: It’s) and fix the spelling of Fischmarkt.
Original sentences: The drips in my new series are done by flinging paint using brushes or a stick. Like the canvasses of Jackson Pollack they convey the affect of a pulsating sky.
A line editor would tackle that verb “to do” in the passive voice (are done). The doer is missing, and that sentence falls flat. A livelier description might rework that statement using the phrase I fling paint.
A copyeditor would correct the spelling (canvases, not canvasses; Pollock, not Pollack; effect, not affect) and add a comma after Pollock.
Both a line editor and a copyeditor would align the artist’s two methods of getting paint to canvas by choosing either singular (using a brush or a stick) or plural (using brushes or sticks).