tail vs bob

tail and bob both are nouns.

Word	Noun	Adjective	Verb	Adverb
tail	Yes	No	Yes	No
bob	Yes	No	Yes	No

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

tail: the posterior part of the body of a vertebrate especially when elongated and extending beyond the trunk or main part of the body
bob: a short or shortened tail of certain animals

Other hyponyms of tail include rattle, brush, bobtail, dock, caudal appendage, uropygium, oxtail, fluke, scut, flag.

As verbs, tail and bob are synonyms defined as:

Other synonyms of tail include dock.

tail (noun)	bob (noun)
the posterior part of the body of a vertebrate especially when elongated and extending beyond the trunk or main part of the body	a short abrupt inclination (as of the head)
the rear part of a ship	a short or shortened tail of certain animals
the rear part of an aircraft	a small float usually made of cork; attached to a fishing line
(usually plural) the reverse side of a coin that does not bear the representation of a person's head	a hanging weight, especially a metal ball on a string
the fleshy part of the human body that you sit on	a long racing sled (for 2 or more people) with a steering mechanism
a spy employed to follow someone and report their movements	a hair style for women and children; a short haircut all around
any projection that resembles the tail of an animal	a former monetary unit in Great Britain
the time of the last part of something

tail (verb)	bob (verb)
remove or shorten the tail of an animal	cut hair in the style of a bob
remove the stalk of fruits or berries	make a curtsy; usually done only by girls and women; as a sign of respect
go after with the intent to catch	remove or shorten the tail of an animal
	move up and down repeatedly in a quick, short movement
	ride a bobsled