tee shirt vs turtleneck

tee shirt and turtleneck both are nouns.

Word	Noun	Adjective	Verb	Adverb
tee shirt	Yes	No	No	No
turtleneck	Yes	No	No	No

As nouns, turtleneck is a hyponym of tee shirt; that is, turtleneck is a word with a more specific, narrower meaning than tee shirt:

Other hyponyms of tee shirt include polo-neck, turtle.

tee shirt (noun)	turtleneck (noun)
a close-fitting pullover shirt	a sweater or jersey with a high close-fitting collar