turtle vs turtleneck

turtle and turtleneck both are nouns.

Word	Noun	Adjective	Verb	Adverb
turtle	Yes	No	Yes	No
turtleneck	Yes	No	No	No

As nouns, turtle and turtleneck are synonyms defined as:

turtle and turtleneck: a sweater or jersey with a high close-fitting collar

Other synonyms of turtle include polo-neck.

turtle (noun)	turtleneck (noun)
any of various aquatic and land reptiles having a bony shell and flipper-like limbs for swimming	a sweater or jersey with a high close-fitting collar
a sweater or jersey with a high close-fitting collar

turtle (verb)	turtleneck (verb)
hunt for turtles, especially as an occupation
overturn accidentally