twirl vs pirouette

twirl and pirouette both are nouns.

Word	Noun	Adjective	Verb	Adverb
twirl	Yes	No	Yes	No
pirouette	Yes	No	Yes	No

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

twirl: the act of rotating rapidly
pirouette: (ballet) a rapid spin of the body (especially on the toes as in ballet)

Other hyponyms of twirl include birling, logrolling.

twirl (noun)	pirouette (noun)
the act of rotating rapidly	(ballet) a rapid spin of the body (especially on the toes as in ballet)
a sharp bend in a line produced when a line having a loop is pulled tight

twirl (verb)	pirouette (verb)
turn in a twisting or spinning motion	do a pirouette, usually as part of a dance
cause to spin