deaf-aid vs hearing aid

deaf-aid and hearing aid both are nouns.

Word	Noun	Adjective	Verb	Adverb
deaf-aid	Yes	No	No	No
hearing aid	Yes	No	No	No

As nouns, deaf-aid and hearing aid are synonyms defined as:

deaf-aid and hearing aid: an electronic device that amplifies sound and is worn to compensate for poor hearing

deaf-aid (noun)	hearing aid (noun)
an electronic device that amplifies sound and is worn to compensate for poor hearing	a conical acoustic device formerly used to direct sound to the ear of a hearing-impaired person
	an electronic device that amplifies sound and is worn to compensate for poor hearing