ALS vs nervous disorder

ALS and nervous disorder both are nouns.

Word	Noun	Adjective	Verb	Adverb
ALS	Yes	No	No	No
nervous disorder	Yes	No	No	No

As nouns, nervous disorder is a hypernym of ALS; that is, nervous disorder 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
nervous disorder: a disorder of the nervous system

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

ALS (noun)	nervous disorder (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