beheading vs decapitation

beheading

noun
  • An instance of a person being beheaded. 

decapitation

noun
  • Beheading; the act of beheading or decapitating. 

  • The ousting or destruction of the ruling body of a government or other organization. 

  • The unseating of a senior politician. 

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