City/Municipality

Cities/municipalities can govern a prefecture-level area.  Examples are Lhasa and Zhikatse in the Tibetan Autonomous Region,  Xining in Qinghai, Golmud, and a few more in Qinghai.  Thus "Lhasa" is a prefecture-level area, which includes urban Lhasa as a county-level element within it; however the Lhasa urban area itself is not a county, but an urban area controlled directly by the province-level element (in this case TAR).