Quick answer
A corner cylinder's front is a true quarter circle whose radius equals the wall side length. A corner bow front's curve is shallower, so it needs a bow depth measurement. For the same wall length, the corner cylinder always holds more.Shape differences
Both have two straight sides against the walls. The corner cylinder's curved front sweeps all the way from one wall to the other in a quarter circle. The corner bow front's panel bulges only modestly beyond the straight line between the wall ends.
Measurement differences
Corner cylinder: one wall side (the radius) and height. Corner bow front: the straight front span between the wall ends, the bow depth from that line to the glass, and height.
Formula differences
Corner cylinder: V = π × r² × H ÷ 4. Corner bow front: V = (S² ÷ 4 + π × S × B ÷ 4) × H.
Which calculator should you use?
Measure the bow depth as a fraction of the front span. If it is close to 0.29 the curve is a quarter circle and you have a corner cylinder. Anything shallower is a corner bow front.
Example comparison
Corner bow front, 34 in span, 4 in bow, 24 in tall
41.1 gal (155.4 L)
Corner cylinder, 24 in walls, 24 in tall
47.0 gal (177.9 L)
Same wall length. The quarter circle front adds about 6 gallons over the shallow bow.