pet vs animal

pet and animal both are nouns.

Word	Noun	Adjective	Verb	Adverb
pet	Yes	Yes	Yes	No
animal	Yes	Yes	No	No

As nouns, animal is a hypernym of pet; that is, animal is a word with a broader meaning than pet:

Other hypernyms of pet include animate being, beast, brute, creature, fauna.

pet (noun)	animal (noun)
a domesticated animal kept for companionship or amusement	a living organism characterized by voluntary movement
a fit of petulance or sulkiness (especially at what is felt to be a slight)
a special loved one

pet (adjective)	animal (adjective)
preferred above all others and treated with partiality	marked by the appetites and passions of the body

pet (verb)	animal (verb)
stroke or caress gently
stroke or caress in an erotic manner, as during lovemaking