How is Islam sunni and shiite related to each other?

Answer 1

They are the two main branches of Islam. The split between Sunni and shiite Islam occurred very early in Islam's history, in the 7th century AD. It had very little to do with any differences in Muslim belief (although there are a few, mostly minor differences), but everything with the question whether the rightful successor to the prophet Muhammed was his father-in-law Abu Bakr or his son-in-law Ali.

Sunni Muslims think is was Abu Bakr, Shia Muslims are followers of Ali ('shia' even means "followers"). In the past, Sunni and Shiite Muslims mostly managed to co-exist peacefully and even intermarried. Today the differences between these two Muslim branches have become intermingled with the struggle for political supremacy in the Middle East between Sunni Saudi Arabia and Shiite Iran.

Answer 2

Sunni and Shiite are two main branches of Islam that differ primarily in their beliefs about the rightful successor to the Prophet Muhammad. The split originated from a historical disagreement over leadership, and the two groups have since developed distinct theological and legal traditions. Despite these differences, both Sunni and Shiite Muslims share core beliefs in the Quran and the five pillars of Islam.