turtleneck collar vs neckband

turtleneck collar and neckband both are nouns.

Word	Noun	Adjective	Verb	Adverb
turtleneck collar	Yes	No	No	No
neckband	Yes	No	No	No

As nouns, neckband is a hypernym of turtleneck collar; that is, neckband is a word with a broader meaning than turtleneck collar:

Other hypernyms of turtleneck collar include collar.

turtleneck collar (noun)	neckband (noun)
a high close-fitting turnover collar	a band that fits around the neck and is usually folded over
	necklace that fits tightly around a woman's neck
	a band around the collar of a garment