What is the diagnostic difference between a headache and a migraine? How do you know a headache is a migraine? What is the key clue to a migraine?

Pattern/course. Migraine are severe intermittent headaches lasting 4 to 72 hours, sometimes unilateral, throbbing, with nausea. There is usually a family histiory and specific trigger factors such as type of food and drink, hunger, smells, lack of sleep etc.