bugaboo vs headache

bugaboo and headache both are nouns.

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

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

Other hypernyms of bugaboo include concern, vexation, worry.

bugaboo (noun)	headache (noun)
a source of concern	something or someone that causes anxiety; a source of unhappiness
an imaginary monster used to frighten children	pain in the head caused by dilation of cerebral arteries or muscle contractions or a reaction to drugs