municipality vs urban area

municipality

noun
  • The governing body of such a district. 

  • A district with a government that typically encloses no other governed districts; a borough, city, or incorporated town or village. 

  • In Mexico and other Spanish- and Portuguese-speaking countries, second-level administrative divisions that may house one or more cities or towns whose head of government may be called mayors or, in Mexico, municipal presidents. 

urban area

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