assignee vs substitute

assignee

noun
  • one to whom a thing is assigned 

  • one to whom rights or property is being transferred 

  • one who is appointed to act or speak in place of another; an agent 

substitute

noun
  • One who enlists for military service in the place of a conscript. 

  • A player who is available to replace another if the need arises, and who may or may not actually do so. 

  • A replacement or stand-in for something that achieves a similar result or purpose. 

verb
  • To remove (a player) from the field of play and bring on another in his place. 

  • To serve as a replacement (for someone or something). 

  • To use in place of something else, with the same function. 

  • To use X in place of Y. 

  • To use Y in place of X; to replace X with Y. 

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