fat-soluble vitamin vs vitamin

fat-soluble vitamin and vitamin both are nouns.

Word	Noun	Adjective	Verb	Adverb
fat-soluble vitamin	Yes	No	No	No
vitamin	Yes	No	No	No

As nouns, vitamin is a hypernym of fat-soluble vitamin; that is, vitamin is a word with a broader meaning than fat-soluble vitamin:

fat-soluble vitamin: any vitamin that is soluble in fats
vitamin: any of a group of organic substances essential in small quantities to normal metabolism

fat-soluble vitamin (noun)	vitamin (noun)
any vitamin that is soluble in fats	any of a group of organic substances essential in small quantities to normal metabolism