heterosexuality vs sexual orientation

heterosexuality

noun
  • The state of being sexually and romantically attracted primarily or exclusively to persons of the opposite sex. 

  • Sexual activity with a person of the opposite sex. 

sexual orientation

noun
  • One's tendencies of sexual attraction, considered as a whole. 

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