visual defect vs disability

visual defect and disability both are nouns.

Word	Noun	Adjective	Verb	Adverb
visual defect	Yes	No	No	No
disability	Yes	No	No	No

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

visual defect: impairment of the sense of sight
disability: the condition of being unable to perform as a consequence of physical or mental unfitness

Other hypernyms of visual defect include disablement, handicap, impairment.

visual defect (noun)	disability (noun)
impairment of the sense of sight	the condition of being unable to perform as a consequence of physical or mental unfitness