dysarthria vs speech disorder

dysarthria and speech disorder both are nouns.

Word	Noun	Adjective	Verb	Adverb
dysarthria	Yes	No	No	No
speech disorder	Yes	No	No	No

As nouns, speech disorder is a hypernym of dysarthria; that is, speech disorder is a word with a broader meaning than dysarthria:

dysarthria: impaired articulatory ability resulting from defects in the peripheral motor nerves or in the speech musculature
speech disorder: a disorder of oral speech

Other hypernyms of dysarthria include defect of speech, speech defect.

dysarthria (noun)	speech disorder (noun)
impaired articulatory ability resulting from defects in the peripheral motor nerves or in the speech musculature	a disorder of oral speech