paraphrenia vs dementia praecox

paraphrenia and dementia praecox both are nouns.

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

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

paraphrenia: a form of schizophrenia characterized by delusions (of persecution or grandeur or jealousy); symptoms may include anger and anxiety and aloofness and doubts about gender identity; unlike other types of schizophrenia the patients are usually presentable and (if delusions are not acted on) may function in an apparently normal manner
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 paraphrenia include schizophrenia, schizophrenic disorder, schizophrenic psychosis.

paraphrenia (noun)	dementia praecox (noun)
a form of schizophrenia characterized by delusions (of persecution or grandeur or jealousy); symptoms may include anger and anxiety and aloofness and doubts about gender identity; unlike other types of schizophrenia the patients are usually presentable and (if delusions are not acted on) may function in an apparently normal manner	any of several psychotic disorders characterized by distortions of reality and disturbances of thought and language and withdrawal from social contact