expanse vs superficies

expanse

noun
  • A wide stretch, usually of sea, sky, or land. 

  • An amount of spread or stretch. 

superficies

noun
  • The area of a two-dimensional surface. 

  • The surface (of something immaterial, especially of the mind or soul). 

  • A building intimately associated with the land on which it is built. 

  • The visible, external surface of a body. 

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