discern vs muddle up

discern

verb
  • To distinguish something as being different from something else; to differentiate. 

  • To perceive, recognize, or comprehend with the mind; to descry. 

  • To detect with the senses, especially with the eyes. 

  • To perceive differences. 

muddle up

verb
  • to confuse (one or more objects with another object or other objects) 

  • To mix together 

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