The lines between tension type headaches and migraines is not really all that clear cut.  There is much overlap between the two and, quite frankly, anyone who has chronic headaches likely has multiple types of headaches that he or she experiences.  This leads to the biggest problem--very few doctors understand how to identify and treat both the structural (tension) headaches and the migraines (most evidence points to a problem with the reactivity of the lining of the blood vessels).  The patient then only gets "half" a treatment and gives up when the headaches return