Could you please tell me the differences between Sunnis and Shī`ahs?
In my opinion, the basic difference between the Shī`ah and the Sunni schools of thought is that in the Shī`ah school the imams (their religious and spiritual leaders) are granted a unique status. It is held these imams cannot err (ma`sūm `ani’l khatā), they are chosen by Allah (mansūs mina’l Allāh) and that they must be followed like Prophets of Allah (muftaridhu’l tāah). It is also believed that their imams receive a revelation of a certain kind.
In other words, though the Prophet (sws) is apparently regarded as the last of the messenger of Allah, yet in reality this fact is virtually denied.
All other differences are offshoots or corollaries of this basic difference.