hebephrenia vs dementia praecox

hebephrenia and dementia praecox both are nouns.

Word	Noun	Adjective	Verb	Adverb
hebephrenia	Yes	No	No	No
dementia praecox	Yes	No	No	No

As nouns, dementia praecox is a hypernym of hebephrenia; that is, dementia praecox is a word with a broader meaning than hebephrenia:

hebephrenia: a form of schizophrenia characterized by severe disintegration of personality including erratic speech and childish mannerisms and bizarre behavior; usually becomes evident during puberty; the most common diagnostic category in mental institutions
dementia praecox: any of several psychotic disorders characterized by distortions of reality and disturbances of thought and language and withdrawal from social contact

Other hypernyms of hebephrenia include schizophrenia, schizophrenic disorder, schizophrenic psychosis.

hebephrenia (noun)	dementia praecox (noun)
a form of schizophrenia characterized by severe disintegration of personality including erratic speech and childish mannerisms and bizarre behavior; usually becomes evident during puberty; the most common diagnostic category in mental institutions	any of several psychotic disorders characterized by distortions of reality and disturbances of thought and language and withdrawal from social contact