"Round Bowl" - A measurement in inches from the center of the two seat bolts on the back edge to the furthest tip of toilet bowl that equals 16.5 or less.

"Elongated Bowl" - A measurement in inches from the center of the two seat bolts on the back edge to the furthest tip of toilet bowl that equals 16.6 or more.

"Wrap Around" - A one piece bowl, with tank that "Wraps," around the seat.