PS... WASTE MANAGEMENT does not offer yard waste removal in our area.
This website scrambled my measurements above. 96 gallon containers can hold approximately 12 kitchen sized bags filled with trash and 64 gallon can hold 8 to 9 bags. The only advantage of the slightly smaller size is that some folks think the 6 inches less in width makes it fit better in a smaller space and that those cans are easier to move around.