One of the two major Kurdish dialects or languages, Sorani is spoken by some 6 million Kurds in southeastern Iraqi Kurdistan and Iran, while Kurmanji is spoken by some 15 million in Turkey and northwestern Iraqi Kurdistan. Both belong to the southwestern group of Iranian languages. It is said that grammatically the two differ from each other as much as English and German. In terms of vocabulary their differences are maybe of the same degree as those between German and Dutch. Nevertheless, the speakers of each are able to communicate with some difficulty.
Major dialects of Sorani include Mukri, Ardalani, Garmiyani, Khushnow, Pizhdar, Warmawa, Kirmanshahi, and Arbili (or Sorani proper). Part of the split between Massoud Barzani's Kurdistan Democratic Party (KDP) and Jalal Talabani's Patriotic Union of Kurdistan (PUK) reflects the fact that the former speak Kurmanji, while the latter speak Sorani. During the time of Mulla Mustafa Barzani and the KDP Politburo of Ibrahim Ahmed, there was a tendency to view Sorani speakers as urban intellectuals and Kurmanji speakers as more backward tribal people. This characterization, of course, was a gross oversimplification.
Historical Dictionary of the Kurds. Michael M. Gunter.