A string trimmer, also called a weed whacker, is a lawn maintenance tool used for removing weeds in hard-to-reach areas and trimming tall grass. A lawn edger, also known as a lawn trimmer, is used to create the line between where the lawn ends and the sidewalk begins. Lawn edgers create a manicured look by removing overgrown grass from the sidewalk area. In short, an edger creates the boundary line between the yard and the sidewalk, and the string trimmer can be used to maintain it. Within Electric Edgers, prices range from $50 to $500.