crown prince vs inheritor

crown prince

noun
  • 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. 

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

inheritor

noun
  • Someone who inherits something; an heir. 

  • A class, etc. that derives from another code element through inheritance. 

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