ataxy vs neurological disease

ataxy and neurological disease both are nouns.

Word	Noun	Adjective	Verb	Adverb
ataxy	Yes	No	No	No
neurological disease	Yes	No	No	No

As nouns, neurological disease is a hypernym of ataxy; that is, neurological disease is a word with a broader meaning than ataxy:

ataxy: inability to coordinate voluntary muscle movements; unsteady movements and staggering gait
neurological disease: a disorder of the nervous system

Other hypernyms of ataxy include nervous disorder, neurological disorder.

ataxy (noun)	neurological disease (noun)
inability to coordinate voluntary muscle movements; unsteady movements and staggering gait	a disorder of the nervous system