Headaches fall under several different categories and subcategories, the two primary ones being Vascular headache and Non-vascular headache.

Under vascular headaches come the following classifications:

Migraine

Classic
Common
Complicated
Variant

Cluster headache

Episodic cluster
Chronic cluster
Chronic paroxysmal hemicrania

Miscellaneous vascular headaches

Carotidynia
Hypertension
Exertional
Hangover
Toxins and drugs
Occlusive vascular disease

Under non-vascular headaches come the following classifications:

Tension headache

Common tension headache
Temporomandibular joint (TMJ) dysfunction

Increased or decreased intracranial pressure
Brain tumours
Sinus infections
Dental infections
Inner or middle ear infections