ALS vs neurological disease

ALS and neurological disease both are nouns.

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

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

ALS: thickening of tissue in the motor tracts of the lateral columns and anterior horns of the spinal cord; results in progressive muscle atrophy that starts in the limbs
neurological disease: a disorder of the nervous system

Other hypernyms of ALS include nervous disorder, neurological disorder, induration, sclerosis.

ALS (noun)	neurological disease (noun)
thickening of tissue in the motor tracts of the lateral columns and anterior horns of the spinal cord; results in progressive muscle atrophy that starts in the limbs	a disorder of the nervous system