A motorized rotary mower works by spinning the single blade in a circle at a high rate of speed. This action has a ripping effect which severs the top part of the grass blade from the bottom. Better models feature a mulching blade which eliminates the need for raking or bagging the clippings. Most rotary mowers tear the grass which leaves the tips shredded, and the tips soon turn brown.
Reel lawn mowers, on the other hand, feature a blade assembly that rotate around a central, horizontal cylinder. As the blade turns it brings the grass into contact with the bed knife. The bed knife is a stationary bar, parallel to the ground, which holds the grass up so that the reel can shear it off. Reel mowers don’t tear your grass like rotary mowers. They cut it like scissors, which makes for a healthier lawn. A sheared cut gives a greener lawn, and is preferred by lawn care professionals.