[SpEEdyBL]

The main differnce between wye and delta is that a wye with x number of turns is basically the same as a delta wound motor with 1.73x turns, so a 1.5d will be a little faster than a 1y.

In theory wye is more efficient than delta.

A wye wound motor fires two phases in series to each other at one time with current going in opposite directions. One coil attracts the rotor, and the other repels the same pole.

A delta wound motor uses all three phases at once (one in series by itself and the other two are connected in a series with current opposite to the phase by itself). I can draw a picture if you would like.