Final answer:
Shi'ite Muslims differ from Sunnis primarily in their belief in a specific lineage of leaders, or Imams, originating from Muhammad's family through his son-in-law Ali. Sunnis believe in a broader qualification for leadership, not limited to Muhammad's direct descendants. The debate over leadership has been central to the split between Shia and Sunni Muslims.
Step-by-step explanation:
Shi'ite Muslims differ from Sunnis based on their belief in a distinct lineage of spiritual leaders known as Imams who succeeded Muhammad. The Shia believe that leadership of the Muslim community should reside within Muhammad's family, specifically through his son-in-law Ali, who they consider as the first Imam. Sunnis, on the other hand, believe that any pious man who is an effective leader and follows Muhammad's example could be a leader of the Muslim community.
For Shi'ites, or Twelvers, Ali represents the origin of a line of twelve infallible Imams, divinely chosen leaders, with the twelfth Imam, Muhammad al-Mahdi, destined to return alongside Jesus to guide the faithful. The Sunnis respect Ali and the twelve Imams but do not ascribe to them the divine right of leadership exclusive to Muhammad's lineage. Instead, they emphasize the sunna, or customs, of the Prophet Muhammad and the interpretation of Islamic law by religious scholars or ulama.