letterhead vs postcard

letterhead

noun
  • Paper marked with a letterhead. 

  • A portion of text at the top of a letter, identifying the sender and often giving their address etc., used for formal correspondence. 

postcard

noun
  • A rectangular piece of thick paper or thin cardboard intended to be written on and mailed without an envelope. In the case of a picture postcard one side carries a picture or photograph. 

verb
  • To send by means of a postcard. 

  • To send a postcard to. 

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