extensively vs fully

extensively

adv
  • To a great extent. 

  • In an extensive manner, widely. 

fully

adv
  • In a full degree; to a full extent. 

  • As a minimum; at least. 

  • In a full manner; without lack or defect. 

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