I think that you must be referring to the divisions of Kohen, Levi and Yisrael. Within the Jewish People there is a type of "spiritual hierarchy". At the "top" are the descendants of the original High Priest, Aharon. They belong to the Kohanic family and were the smallest in number. They officiated in the Temple and led the Services, led by the High Priest. Aiding them in the Temple were the Levites. They were larger in number than the Kohanim and their task was to serve as guards to the Temple and to sing and play musical instruments during the Services. The vast majority of the Jewish People, however, were known as Israelites. That included anyone who was not a part of the Kohen or Levite families, and belonged to eleven of the twelve tribes of Israel.
