executioner vs hatchet man

executioner

noun
  • A hit man, especially being in some organization. 

  • An official person who carries out the capital punishment of a criminal. 

hatchet man

noun
  • A male who carries out brutal and unpleasant duties on behalf of another, such as firing dead wood employees. 

  • A male professional killer or gunman. 

  • A male hatchet-wielding participant in a Chinese-American tong war. 

How often have the words executioner and hatchet man occurred in a corpus of books? (source: Google Ngram Viewer )