batata vs boniato

batata

noun
  • sweet potato (foodstuff) 

  • sweet potato (plant) 

boniato

noun
  • A Cuban type of sweet potato with light-colored flesh that is drier and less sweet than the varieties typical in the US (Ipomoea batatas). 

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