confederation vs unification

confederation

noun
  • The act of forming an alliance. 

  • A union or alliance of states or political organizations. 

unification

noun
  • The state of being unified. 

  • Given two terms, their join with respect to a specialisation order. 

  • The act of unifying. 

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