significant vs substantial

significant

adj
  • Reasonably large in number or amount. 

  • Having a low probability of occurring by chance (for example, having high correlation and thus likely to be related). 

  • Having a covert or hidden meaning. 

  • Having a noticeable or major effect. 

  • Signifying something; carrying meaning. 

noun
  • That which has significance; a sign; a token; a symbol. 

substantial

adj
  • Large in size, quantity, or value; ample; significant. 

  • Most important; essential. 

  • Not imaginary; real; actual; true; veritable. 

  • Having a substance; actually existing. 

  • Corporeal; material; firm. 

  • Possessed of goods or an estate; moderately wealthy. 

  • Satisfying; having sufficient substance to be nourishing or filling. 

  • Having good substance; strong; stout; solid; firm. 

noun
  • Anything having substance; an essential part. 

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