mail carrier vs post office

mail carrier

noun
  • A person employed to deliver mail. 

post office

noun
  • An organisation that delivers letters. 

  • A party game involving the exchange of kisses. 

  • A place (building, office, shop, or counter) concerned with the business of delivering letters, post or mail and selling stamps, etc. 

How often have the words mail carrier and post office occurred in a corpus of books? (source: Google Ngram Viewer )