Rough cut mowers are tough mowers, designed to handle overgrown brush, weeds, and saplings. They aren't designed to mow regular grass like your lawn.
The blades on a rough cut mower aren't like a traditional rotary mower. Instead, they are equipped with two hardened steel blades that swing back and forth, like a pendulum. These blades can pulverize branches up to 3" thick.
Equipped with an articulating hitch, tow-behind rough cut mowers can be offset to the left or right of your towing vehicle.
This is important when cutting through brush so you don't have to drive directly through the wilderness. It's also useful when mowing under low hanging trees or in ditches.