accomplishment vs feather in one's cap

accomplishment

noun
  • Something accomplished; an achievement. 

  • The act of accomplishing; completion; fulfilment. 

  • The lexical aspect (aktionsart) of verbs or predicates that change over time until a natural end point. 

  • That which completes, perfects, or equips thoroughly; acquirement; attainment; that which constitutes excellence of mind, or elegance of manners, acquired by education or training. 

feather in one's cap

noun
  • An accomplishment; particularly one that is flaunted or boasted of. 

  • He thinks it is quite a feather in his cap that he figured it out for himself. 

  • Used other than figuratively or idiomatically: see feather, cap. 

How often have the words accomplishment and feather in one's cap occurred in a corpus of books? (source: Google Ngram Viewer )