freedom fighter vs rebel

freedom fighter

noun
  • A person involved in armed conflict against an occupation, or oppressive government, etc.; a revolutionary, an insurgent, a rebel or insurrectionist. 

rebel

noun
  • A person who resists an established authority, often violently. 

  • Synonym of Confederate: a citizen of the Confederate States of America, especially a Confederate soldier. 

verb
  • To resist or become defiant toward an authority. 

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