Swales: Swales are shallow, elongated depressions in the land that collect and move water. They are visible in the landscape and often highlight the movement of water through their material choices and layout. Swales move water, but they also slow it down and allow it to percolate back into the ground to improve water quality.
Subdrainage: Subdrainage consists of underground constructed drainage systems, including drainpipes and drain inlets, that collect and move water. Because it is buried in the landscape, subdrainage is often invisible to us. Buried drainage moves water quickly and efficiently across the landscape.
A mixture of the two: Swales can be used in conjunction with subdrainage. An example would be when a swale is used to move water from a roof downspout across the landscape to a drain inlet.