attaché case vs portfolio

attaché case

noun
  • A box-style briefcase, scrunched over a hinged frame that opens into two compartments. 

portfolio

noun
  • A case for carrying papers, drawings, photographs, maps and other flat documents. 

  • The post and the responsibilities of a cabinet minister or other head of a government department. 

  • A collection of assets; (figurative) any collection of things considered as investments or assets. 

  • A range of products. 

  • The collection of such documents, especially the works of an artist or photographer. 

  • The group of investments and other assets held by an investor. 

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