The system is AC, and yes, there's a substantial difference between the AC and DC systems. DC systems have very little loss.
That's why, if they're going long distances, a lot of the utilities, such as Manitoba's and Quebec's, have DC lines. With very little loss, they can move a lot of power.
With the DC lines, too, you have control at each end. You can really control the amount of power that flows on that line. With AC lines, there's a factor.... Wire has a resistance, so it heats up, and you lose power as you transmit it a long way.