difference of opinion vs squabble

difference of opinion

noun
  • A disagreement. 

squabble

noun
  • A minor fight or argument. 

verb
  • To disarrange, so that the letters or lines stand awry and require readjustment. 

  • To participate in a minor fight or argument; to quarrel. 

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