tail end vs fag end

tail end and fag end both are nouns.

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

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

Other synonyms of tail end include tail.

tail end (noun)	fag end (noun)
the fleshy part of the human body that you sit on	the frayed end of a length of cloth or rope
any projection that resembles the tail of an animal	the time of the last part of something
the time of the last part of something