insignificant vs nonessential

insignificant

adj
  • Not significant; not important, inconsequential, or having no noticeable effect. 

  • Without meaning; not signifying anything. 

nonessential

adj
  • Not required; not essential. 

noun
  • Something that is not essential. 

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