archbishop vs hierarch

archbishop

noun
  • A senior bishop who is in charge of an archdiocese, and presides over a group of dioceses called a province (in Catholicism, Eastern Orthodoxy, Anglicanism, etc.) 

hierarch

noun
  • A title of bishops in their role as ordinaries (arbiters of canon law) over their respective dioceses. 

  • One who has high and controlling authority in sacred things; the chief of a sacred order. 

How often have the words archbishop and hierarch occurred in a corpus of books? (source: Google Ngram Viewer )