county seat vs municipality

county seat

noun
  • The city in which the offices of county government are located. 

municipality

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

  • The governing body of such a district. 

  • 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. 

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