Are quick couplings the same thing as reducers, female to male, etc.? Are they just called different names? If so, what is the difference?

Three kinds are different, quick connector is able to quickly pick up and dial down, reducer connector is not necessarily fast, it is one end of the big end of the small, connected to the diameter will be smaller than the other end, and yin and yang fittings of the two ends of the A head B head, depending on the situation need to be connected to the two ends can be connected to the two ends can be determined in accordance with your needs, that's it