illusion vs phantasy

illusion

noun
  • A misapprehension; a belief in something that is in fact not true. 

  • Anything that seems to be something that it is not. 

  • A magician’s trick. 

  • The state of being deceived or misled. 

phantasy

noun
  • The innate, mental image of an object; the link between instinct and reality. 

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