piece of tail vs copulation

piece of tail and copulation both are nouns.

Word	Noun	Adjective	Verb	Adverb
piece of tail	Yes	No	No	No
copulation	Yes	No	No	No

As nouns, copulation is a hypernym of piece of tail; that is, copulation is a word with a broader meaning than piece of tail:

piece of tail: slang for sexual intercourse
copulation: sexual activity between individuals, especially the insertion of a man's penis into a woman's vagina until orgasm and ejaculation occur

piece of tail (noun)	copulation (noun)
slang for sexual intercourse	sexual activity between individuals, especially the insertion of a man's penis into a woman's vagina until orgasm and ejaculation occur