run away vs turn tail

run away

verb
  • To flee by running. 

  • To leave home, or other place of residence, usually unannounced, or to make good on a threat, with such action usually performed by a child or juvenile. 

  • To become a runaway. 

turn tail

verb
  • To turn away from someone or something, in preparation for running away; to reverse direction; to leave or flee. 

How often have the words run away and turn tail occurred in a corpus of books? (source: Google Ngram Viewer )