Sunnah And Hadees
Because the Sunnah was initiated by The Prophet himself and the Sahaba adopted that sunnat. But the Hadith was initiated by Muhadiseen (Hadith Collectors) and not the Prophet and neither the Sahaba. Sunnat is preserved in the Amaal(Actions) of the Ummat. Sunnat reached us through the Practice of Muslims in Subcontinent. This Sunnat has reached us by collective unifying consensus of the Ummat and transmitted through Generations from the Companions of the Prophet to their Companions and so on. But Hadith has no such consensus within the Ummat and neither did it reached us Through Uninterrupted continuity in transmission.