polo-neck collar vs turtleneck collar

polo-neck collar and turtleneck collar both are nouns.

Word	Noun	Adjective	Verb	Adverb
polo-neck collar	Yes	No	No	No
turtleneck collar	Yes	No	No	No

As nouns, polo-neck collar and turtleneck collar are synonyms defined as:

polo-neck collar and turtleneck collar: a high close-fitting turnover collar

polo-neck collar (noun)	turtleneck collar (noun)
a high close-fitting turnover collar	a high close-fitting turnover collar