activity vs incentive

activity

noun
  • Something done for pleasure or entertainment, especially one involving movement or an excursion. 

  • The lexical aspect (aktionsart) of verbs or predicates that change over time and have no natural end point. 

  • Something done as an action or a movement. 

  • The state or quality of being active; activeness. 

  • The number of radioactive decays per unit time. Unit for it: becquerel or curie 

  • The propery of substances to react with other substances 

incentive

noun
  • Something that motivates, rouses, or encourages. 

  • A bonus or reward, often monetary, to work harder. 

adj
  • Inciting; encouraging or moving; rousing to action; stimulating. 

  • Serving to kindle or set on fire. 

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