baron vs crown prince

baron

noun
  • The male ruler of a barony. 

  • A male member of the lowest rank of English nobility (the equivalent rank in Scotland is lord). 

  • A person of great power in society, especially in business and politics. 

  • A prisoner who gains power and influence by lending or selling goods such as tobacco. 

  • Any of various nymphalid butterflies of the genus Euthalia. 

  • A baron of beef, a cut made up of a double sirloin. 

crown prince

noun
  • A person designated and raised to become the next king. 

  • A person expected to inherit or take over an enterprise or undertaking once its current manager retires or dies. 

  • A person designated and raised to become the next emperor. 

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