What is a main difference between twelvers and zaydi shi'is?

The main difference between Twelver and Zaydi Shi'is lies in their beliefs about the line of leadership and the Imamate. Twelver Shi'is believe in a succession of twelve Imams, with the twelfth Imam, Muhammad al-Mahdi, currently in occultation and expected to return as a messianic figure. In contrast, Zaydi Shi'is do not adhere to a fixed line of Imams and believe that any qualified descendant of the Prophet Muhammad can lead the community, allowing for a more flexible interpretation of leadership. This fundamental difference shapes their religious practices and theological perspectives.