expository vs presentational

expository

adj
  • Serving to explain, explicate, or elucidate; expositive; of or relating to exposition. 

presentational

adj
  • Of, or pertaining to, presentation(s). 

noun
  • A clause using existential "there" with a verb other than a form of "be", as in "There followed a brief silence". 

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