Here's a link to the site about PTSD that the U.S. Department of Veteran Affairs has available that describes the differences between PTSD and Complex PTSD. The difference isn't the length of time the sufferer has the symptoms or multiple diagnoses, it's the duration of the trauma and the differences in the symptoms and their severity due to the prolonged trauma. Those with Complex PTSD have experienced trauma over a longterm period of time as opposed to one event.
http://www.ncptsd.va.gov/facts/speci...plex_ptsd.html