professor vs teacher

professor

noun
  • A teacher or faculty member at a college or university regardless of formal rank. 

  • The most senior rank for an academic at a university or similar institution, informally also known as "full professor." 

  • A pianist in a saloon, brothel, etc. 

  • The puppeteer who performs a Punch and Judy show; a Punchman. 

teacher

noun
  • A person who teaches, especially one employed in a school. 

  • The index finger; the forefinger. 

  • An indication; a lesson. 

  • The second highest office in the Aaronic priesthood, held by priesthood holders of at least the age of 14. 

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