Answer
Harold,
The difference between the 2 and 3 wire pumps is that the 2-wire (actually 3 because there is a ground) includes all the pump starting components inside the pump which is located down in the well. The 3-wire (actually 4 because there is a ground) connects to a control box above ground. this control box includes all the pump starting components, i.e, quick disconnect relay, overloads and capacitors so if there is a problem and one of those components is the cause of the pump failing, it is much easier to replace those components.
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