The Shia belief is also that the descendant of Muhammed who is elected as the new leader is appointed by god and infallible. To me the easiest similarity that I can draw from this is that the Shia faith is similar to the Catholics in Christianity where the one world wide leader is the equivalent of the pope. One difference between Christians & Muslims in this regard is that there does seem to be a lot of strife between the two branches of Islam. The Economist recently ran this article about the current status of the infighting between the two branches. Not that Christians haven't been doing a lot of infighting in history, but most of that was settled a few hundred years ago.
You can read more about the differences between Shia & Muslims on About.com.