rump vs tail end

rump and tail end both are nouns.

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

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

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