diplomacy vs etiquette

diplomacy

noun
  • The art and practice of conducting international relations by negotiating alliances, treaties, agreements etc., bilaterally or multilaterally, between states and sometimes international organizations, or even between polities with varying status, such as those of monarchs and their princely vassals. 

  • Tact and subtle skill in dealing with people so as to avoid or settle hostility. 

etiquette

noun
  • The customary behavior of members of a profession, business, law, or sports team towards each other. 

  • The forms required by a good upbringing, or prescribed by authority, to be observed in social or official life; observance of the proprieties of rank and occasion; conventional decorum; ceremonial code of polite society. 

  • A label used to indicate that a letter is to be sent by airmail. 

  • 2012, July 15. Richard Williams in Guardian Unlimited, Tour de France 2012: Carpet tacks cannot force Bradley Wiggins off track 

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