biography vs novella

biography

noun
  • The art of writing this kind of story. 

  • A person's life story, especially one published. 

verb
  • To write a biography of. 

novella

noun
  • A short novel or long short story. 

  • Synonym of novel (“new legal constitution in Ancient Rome”) 

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