competency vs functionality

competency

noun
  • The ability to perform some task; competence. 

  • Implicit knowledge of a language’s structure. 

  • Meeting specified qualifications to perform. 

functionality

noun
  • The ability to do a task, performance, or execution; a set of functions that something is able or equipped to perform. 

  • The presence of a functional group. 

  • In United States trademark law, the tendency of a product design to serve a function other than identification of the product, preventing that design from being protected as a trademark. 

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