mock turtleneck vs polo-neck

mock turtleneck and polo-neck both are nouns.

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

As nouns, polo-neck is a hypernym of mock turtleneck; that is, polo-neck is a word with a broader meaning than mock turtleneck:

mock turtleneck: A sweater with a short turtleneck collar that does not fold down.
polo-neck: a sweater or jersey with a high close-fitting collar

Other hypernyms of mock turtleneck include turtle, turtleneck.

mock turtleneck (noun)	polo-neck (noun)
A sweater with a short turtleneck collar that does not fold down.	a sweater or jersey with a high close-fitting collar