workgroup vs working group

workgroup

noun
  • A group of workers engaged in a series of collaborative tasks who usually work together. 

  • A computer network created for use by such groups. 

working group

noun
  • Any more or less formal team working for a specific purpose. 

  • An interdisciplinary collaboration of researchers working on new research activities that would be difficult to develop under traditional funding mechanisms such as federal agencies. 

How often have the words workgroup and working group occurred in a corpus of books? (source: Google Ngram Viewer )