Typically migraine and muscle contraction headaches are thought to be different disorders. Recently some investigators have argued that these headache categories are quantitatively, but not qualitatively distinct. Studies of vasomotor and electromyographic (EMG) reflexes and treatments for these headaches were reviewed to elucidate similarities and differences. Similarities include for both types of headaches high levels of tension in the muscles of the head and neck, a vasoconstrictive component, a responsiveness to treatment by relaxation or reduction of frontalis muscle tension. Differences between migraine and muscle contraction headaches relate to the status of the temporal artery between and during headaches and the standard medical treatments used for each. Systematic research is needed to establish if fundamental differences exist between these two major categories of headache.