chief executive vs commander in chief

chief executive

noun

  • Chief executive officer. 

  • The president of the United States. 

  • The head of government of Hong Kong 

  • The head of government of Macau 

  • The governor of a U.S. state. 

commander in chief

noun

  • Supreme commander of the armed forces of an entire country. 

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