taro vs root vegetable

taro and root vegetable both are nouns.

Word	Noun	Adjective	Verb	Adverb
taro	Yes	No	No	No
root vegetable	Yes	No	No	No

As nouns, root vegetable is a hypernym of taro; that is, root vegetable is a word with a broader meaning than taro:

taro (noun)	root vegetable (noun)
tropical starchy tuberous root	any of various fleshy edible underground roots or tubers
herb of the Pacific islands grown throughout the tropics for its edible root and in temperate areas as an ornamental for its large glossy leaves
edible starchy tuberous root of taro plants