jumper vs polo-neck

jumper and polo-neck both are nouns.

Word	Noun	Adjective	Verb	Adverb
jumper	Yes	No	No	No
polo-neck	Yes	No	No	No

As nouns, polo-neck is a hyponym of jumper; that is, polo-neck is a word with a more specific, narrower meaning than jumper:

Other hyponyms of jumper include cardigan, pullover, slipover, turtle, turtleneck.

jumper (noun)	polo-neck (noun)
(basketball) a player releases the basketball at the high point of a jump	a sweater or jersey with a high close-fitting collar
a sleeveless dress resembling an apron; worn over other clothing
a loose jacket or blouse worn by workmen
a small connector used to make temporary electrical connections
a coverall worn by children
a crocheted or knitted garment covering the upper part of the body
an athlete who competes at jumping
a person who jumps