dysplasia vs aplasia

dysplasia and aplasia both are nouns.

Word	Noun	Adjective	Verb	Adverb
dysplasia	Yes	No	No	No
aplasia	Yes	No	No	No

As nouns, aplasia is a hyponym of dysplasia; that is, aplasia is a word with a more specific, narrower meaning than dysplasia:

dysplasia: abnormal development (of organs or cells) or an abnormal structure resulting from such growth
aplasia: failure of some tissue or organ to develop

Other hyponyms of dysplasia include fibrous dysplasia of bone, hypertrophy, hyperplasia, hypoplasia, anaplasia.

dysplasia (noun)	aplasia (noun)
abnormal development (of organs or cells) or an abnormal structure resulting from such growth	failure of some tissue or organ to develop