advisor vs counselor

advisor

noun
  • One who offers advice. 

  • A xiangqi piece, that is moved one point diagonally and confined within the palace. 

counselor

noun
  • A professional who counsels people, especially on personal problems. 

  • A children’s supervisor, usually at camp. 

  • A school counselor, often in a specialty such as careers, education, or health. 

  • An attorney. 

  • A high ranking diplomat, usually just below an ambassador or minister. 

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