aphonia vs defect of speech

aphonia and defect of speech both are nouns.

Word	Noun	Adjective	Verb	Adverb
aphonia	Yes	No	No	No
defect of speech	Yes	No	No	No

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

Other hypernyms of aphonia include speech defect, speech disorder.

aphonia (noun)	defect of speech (noun)
a disorder of the vocal organs that results in the loss of voice	a disorder of oral speech