It seems to be only in that region. I can't speak for anywhere else, but here in the states, the two groups seem to get along just fine, even as far as to have joint events in my neighborhood, and welcome jews and christians to join the festivities. From what I here on this forum though, I gather it's a different affair in the UK.
The similarity is in the structure of clerics (ie, kind of like cardinals or bishops)
Sunni = Protestant Structure
Shia = Catholic Structure (It's sort of like the Catholic church, but with no pope figure, so they aren't as unified, but they all consider themselves brothers and sisters of the shia)