psychotherapy vs psychiatry

psychotherapy and psychiatry both are nouns.

Word	Noun	Adjective	Verb	Adverb
psychotherapy	Yes	No	No	No
psychiatry	Yes	No	No	No

As nouns, psychiatry is a hypernym of psychotherapy; that is, psychiatry is a word with a broader meaning than psychotherapy:

psychotherapy: the branch of psychiatry concerned with psychological methods
psychiatry: the branch of medicine dealing with the diagnosis and treatment of mental disorders

Other hypernyms of psychotherapy include psychological medicine, psychopathology.

psychotherapy (noun)	psychiatry (noun)
the treatment of mental or emotional problems by psychological means	the branch of medicine dealing with the diagnosis and treatment of mental disorders
the branch of psychiatry concerned with psychological methods