sugar baby vs sweetheart

sugar baby

noun
  • The younger recipient (usually female or a bottom) of interest from a sugar daddy or sugar mama, especially financial and romantic in an intergenerational relationship 

  • A term of endearment; sweetheart. 

sweetheart

noun
  • A person very much liked or loved by someone, especially when both partners are young. 

  • A person who is always very kind. 

  • A female member of a college or university fraternity. 

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