rivalry vs tug-ofwar

rivalry

noun
  • The characteristic of being a rivalrous good, such that it can be consumed or used by only one person at a time. 

  • An ongoing relationship between (usually two) rivals who compete for superiority. 

  • Any competition between two or more things or factors. 

tug-ofwar

How often have the words rivalry and tug-ofwar occurred in a corpus of books? (source: Google Ngram Viewer )