tail end vs rump

tail end and rump both are nouns.

Word	Noun	Adjective	Verb	Adverb
tail end	Yes	No	No	No
rump	Yes	No	No	No

As nouns, tail end and rump are synonyms defined as:

tail end (noun)	rump (noun)
the fleshy part of the human body that you sit on	the part of an animal that corresponds to the human buttocks
any projection that resembles the tail of an animal	the fleshy part of the human body that you sit on
the time of the last part of something	fleshy hindquarters; behind the loin and above the round