chief executive vs chief executive officer

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. 

chief executive officer

noun
  • The highest-ranking corporate officer or executive officer of a corporation, company, or agency, responsible for carrying out the policies of the board of directors on a day-to-day basis; CEO. 

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