neurosurgeon vs surgeon

neurosurgeon and surgeon both are nouns.

Word	Noun	Adjective	Verb	Adverb
neurosurgeon	Yes	No	No	No
surgeon	Yes	No	No	No

As nouns, surgeon is a hypernym of neurosurgeon; that is, surgeon is a word with a broader meaning than neurosurgeon:

neurosurgeon: someone who does surgery on the nervous system (especially the brain)
surgeon: a physician who specializes in surgery

Other hypernyms of neurosurgeon include operating surgeon, sawbones.

neurosurgeon (noun)	surgeon (noun)
someone who does surgery on the nervous system (especially the brain)	a physician who specializes in surgery