customer service vs help desk

customer service

noun
  • A department that provides services to existing customers. 

  • The act of providing services to customers before, during and after a purchase. 

help desk

noun
  • A section of an organization offering specialist advice to customers or users who have problems, especially with computer equipment or systems. 

How often have the words customer service and help desk occurred in a corpus of books? (source: Google Ngram Viewer )