alienist vs psychiatrist

alienist and psychiatrist both are nouns.

Word	Noun	Adjective	Verb	Adverb
alienist	Yes	No	No	No
psychiatrist	Yes	No	No	No

As nouns, psychiatrist is a hypernym of alienist; that is, psychiatrist is a word with a broader meaning than alienist:

alienist: a psychiatrist and specialist in the legal aspects of mental illness
psychiatrist: a physician who specializes in psychiatry

Other hypernyms of alienist include head-shrinker, shrink.

alienist (noun)	psychiatrist (noun)
a psychiatrist and specialist in the legal aspects of mental illness	a physician who specializes in psychiatry