What is the difference between a headache and a migraine?

What is the difference between a headache and a migraine?

Migraines are headaches, but not all headaches are migraines.  So, a migraine is a type of headache.  There are many other types of headaches including:  tension headache, cluster headache, cervicogenic headache, trigeminal neuralgia, occipital neuralgia to name a few.