btw I believe there are too many levels of local authorities here in Poland - god knows what we need those powiats for
The important distinction is that
powiat is a governmental structure, whereas
gmina and
województwo are self-governmental or local governmental ones. Hence
starosta - head of the powiat is never elected in a local election, but the person is nominated by the central government or wojewoda [I don't remember precisely]. The prerogatives of
powiat are also different from those of the
gminas [powiat is a bunch of
gminas]. On the
województwo level, there exist a kind of a "double" administration with separate prerogatives however, with
wojewoda, a not-elected person representing the central government within the
województwo, and
sejmik województwa, an elected body with its head "marszałek województwa" being elected by the members of
sejmik rather than by universal voivodship suffrage.
