dysarthria vs speech defect

dysarthria and speech defect both are nouns.

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

As nouns, speech defect is a hypernym of dysarthria; that is, speech defect 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 defect: a disorder of oral speech

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

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