What is the reason for the difference between Sunni Muslims and others, and how do they differ from the prevailing situation of other Muslims?

The previous nations split, and this nation will split into seventy-three sects, all of them in the Fire except one, which is those who are upon what the Prophet, peace and blessings be upon him, and his companions were upon. The origin of this truth is the Holy Quran and the Prophetic Sunnah, and whoever deviates from them has deviated from the truth. Ahl al-Sunnah wal-Jama'ah are those who adhere to the Quran and Sunnah, and follow the righteous predecessors from the Companions and the Tabi'in, for in their following lies truth and guidance.