DIFFERENCES Shias and Sunnis

Here are differences between Shias and Sunnis:
Authority: Sunnis can pick and choose among several schools of interpretation of Islamic law. Shias are supposed to have an allegiance to an ayatollah (which means "sign of God") whose rulings are considered absolutely authoritative. But there are several so-called "grand ayatollahs" and no universally acknowledged Shia leader.
Independence from government: The major Sunni schools are government-financed. Shias, however, have a tradition of giving a fifth of their income to their ayatollah to pay for religious education and other functions. The contributions also give considerable economic power to the ayatollahs.
Judicial reasoning: For both Shia and Sunni, the most respected religious authorities tend to be jurists, not theologians. Their role is to decide how the Koran and hadiths should be applied to current conditions. Shias emphasize adapting the law to conditions in the world, rather than just examining the sacred texts, experts say. This emphasis on logic and reasoning, what in Arabic is called ejtehad, has led Shia scholars to confront issues such as cloning, rights of women in divorce and fertility research more aggressively than their Sunni counterparts. For most of their history, Shia scholars understood their role to be critics who told government authorities when they were not acting in accord with Islamic law. In Iran, the top religious authorities in Iran have veto power over laws passed by the secular government.
Temporary marriage: In Sunni tradition, this is an element of early Islam that is no longer valid. Shias consider the practice of marriages that expire at a fixed time still appropriate in principle, even if they are seldom performed. Supporters say temporary marriage simply recognizes the reality of sexual needs or that it gives couples a chance to test their compatibility. Opponents say it's a way to oppress women and evidence of the corruption of Shia.
Mohammed's successor: Sunnis say the leadership of the fledgling Muslim nation went, as it should have, to a trusted companion of Mohammed after his death, traditionally set in A.D. 632. Shias say the prophet had publicly declared that his successor should be his cousin and son-in-law, Ali, and future leaders were to be selected only from his descendants. However, three caliphs, or leaders, were selected. Today, Ali, his two sons and nine of their descendants are revered by Shias as the only true successors to Mohammed. Sunnis regard Ali as an important spiritual leader but believe Mohammed gave no special instructions about the role his family was to play in Muslim leadership. Shia tradition holds that only Ali and his descendants possessed complete and perfect understanding of the Koran. Shia tradition also teaches that Ali and 10 of his sacred successors, called imams, were stabbed, poisoned or slaughtered on the battlefield by other Muslims over more than 200 years. Most Shias believe the 12th imam was commanded by God to go into hiding 1,072 years ago -- and is still alive, awaiting God's commandment to return and bring justice to the world.
Other differences: The exact timing of prayers, how to wash before worship, and upon what surface heads can rest in prayer can vary. Those differences are enough that some Sunnis declare Shias to be unbelievers.