Ditch vs Swale
Ditch - A long and somewhat narrow uncovered hollow or Trench dug in the ground to recieve and/or conduct water
Trench - A long and narrow, often vertically sided excavation made for the placement of pipe, wire, and footings, or for the conduction of water.
Swale - A moist, usually grassy area in low-lying land or an easy -sided drainage trench through a park or a lawn.