Logic states if you have the same amount of air available to push the water out, you will be able to deliver the same amount of water between the pump cycles regardless whether the tank has a diaphragm separating the air from the water.
As discussed last month, the primary function of a pressure tank in a pumped water system is to store water under pressure so the pump does not have to come on every time there is a small, intermittent demand for water. The amount of usable water stored in a pressure tank is the drawdown, and is the amount of water that can be drawn from the tank between the time the pressure switch cuts out, turning off the pump, and cuts back in, turning the pump on. Tanks are sized with enough drawdown to allow the pump to run a minimum of one minute between cycles, letting the motor cool, as recommended by the motor manufacturers.
There are two types of pressure tanks, captive-air tanks (also called pre-charged, diaphragm, or bladder tanks), and conventional tanks, (also known as galvanized, ASME, and epoxy-lined tanks). In this article, we will use the terms "captive air" and "conventional" to differentiate the two types of tanks.