hilltop vs mountain

hilltop

noun
  • The peak or crest of a hill. 

mountain

noun
  • An elevation of land of considerable dimensions rising more or less abruptly, forming a conspicuous figure in the landscape, usually having a small extent of surface at its summit. 

  • A difficult task or challenge. 

  • Something very large in size or quantity; a huge amount; a great heap. 

  • Wine from Malaga made from grapes that grow on a mountain. 

  • A woman's large breast. 

  • The twenty-first Lenormand card. 

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