on the surface vs significant

on the surface

prep
  • apparently, outwardly; superficially 

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. 

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