instructional vs pedagogical

instructional

adj
  • Intended for purposes of instruction, for teaching. 

noun
  • A book, film, etc. intended to instruct. 

pedagogical

adj
  • Of, or relating to pedagogy; teaching. 

  • Haughty and formal. 

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