bravery vs heroism

bravery

noun
  • Being brave, courageousness. 

  • A brave act. 

  • Splendor, magnificence. 

heroism

noun
  • The qualities characteristic of a hero, such as courage, bravery, fortitude, selflessness, etc.; the display of such qualities. 

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