Service request vs Change request

As I was studying for ITIL foundation v2011 exam, I came upon interesting review questions which needs more clarification.  These are those that I researched & clarified along this journey:

Service request vs Change request
service request =  request by standard users via service desk and is usually a fulfilled through Request fulfillment
Change requests = requests for modifications required in any part of the Services (Service management systems or underlying systems and components)

more about this:

Service Requests vs. Changes