I worked at an Ohio Edison power plant starting in the late 70s.We used the term out of phase because if they were both the same leg your meter would read 120 volts instead of 240 leg to leg.The two hot wires alternate as return paths back to the power plant.We used to argue with the engineers all the time about the terminology.Ther power plant is still there so we must have been installing and repairing the equipment correctly.If you look at the internet site How Stuff Works and look up power grid they use the same terminology I do.I am a member of The Utility Workers Union Of America local 457.