"Hadith or Sunnah is the second source of Shariah. Muslim scholarship done great job in preservation, compilation and transformation of Hadith and sciences of Hadith. Science of Mukhtalif-ul-Hadith is one of the important branch of Hadith Sciences. Imam Tahawi (321 A.H) & Ibn-e-Foark have contributed tremendously to the genre of Mukhtalif ul Hadith and Muskhil-ul-Hadith. Both these personages have evolved various rules related to it and have complied their books "Mushkilul Asar" and "Mushkil ul Hadith" respectively. This article throws light on the characteristics and differences of the both books."