doctor vs veterinarian

doctor and veterinarian both are nouns.

Word	Noun	Adjective	Verb	Adverb
doctor	Yes	No	Yes	No
veterinarian	Yes	No	No	No

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

doctor (noun)	veterinarian (noun)
children take the roles of physician or patient or nurse and pretend they are at the physician's office	a doctor who practices veterinary medicine
a licensed medical practitioner
a person who holds Ph.D. degree (or the equivalent) from an academic institution

doctor (verb)	veterinarian (verb)
give medical treatment to
alter and make impure, as with the intention to deceive
restore by replacing a part or putting together what is torn or broken