curator vs librarian

curator

noun
  • A person who manages, administers or organizes a collection, either independently or employed by a museum, library, archive or zoo. 

  • A member of a curatorium, a board for electing university professors, etc. 

  • One appointed to act as guardian of the estate of a person not legally competent to manage it, or of an absentee; a trustee. 

librarian

noun
  • A person who processes and organizes information. 

  • The keeper, manager of a library. 

  • One who cares for the publications, files etc. in a library, whether staff or volunteer. 

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