cluster headache vs headache

cluster headache and headache both are nouns.

Word	Noun	Adjective	Verb	Adverb
cluster headache	Yes	No	No	No
headache	Yes	No	No	No

As nouns, headache is a hypernym of cluster headache; that is, headache is a word with a broader meaning than cluster headache:

cluster headache: a painful recurring headache associated with the release of histamine from cells
headache: pain in the head caused by dilation of cerebral arteries or muscle contractions or a reaction to drugs

Other hypernyms of cluster headache include cephalalgia, head ache.

cluster headache (noun)	headache (noun)
a painful recurring headache associated with the release of histamine from cells	something or someone that causes anxiety; a source of unhappiness
	pain in the head caused by dilation of cerebral arteries or muscle contractions or a reaction to drugs