piece of art vs technique

piece of art

noun
  • Synonym of work of art 

technique

noun
  • The practical aspects of a given art, occupation etc.; formal requirements. 

  • Practical ability in some given field or practice, often as opposed to creativity or imaginative skill. 

  • A method of achieving something or carrying something out, especially one requiring some skill or knowledge. 

How often have the words piece of art and technique occurred in a corpus of books? (source: Google Ngram Viewer )