IN AN AC CONFIGURATION, WHY ISN'T THE NEUTRAL WIRE LIVE TOO?

OK, On a typical AC generator,as the coil spins right in between the two magnets, should the current along the two wires interchange between + and - respectively due to the different polarities of the magnets? This should cause the two wires to be live (hot) but this is not the case in reality. How does it happen that one of the wires is LIVE(Hot) and the other (cold) if they are doing the same thing back from the power station? Is is because one of them is grounded? What if it wasn't grounded? Would they both be live, with respect to earth?? Please I am confused. I need to know in detail how there happens to be a LIVE and a NEUTRAL if they are both interchanging back at the power plant! Pleas!