veggie vs greens

veggie and greens both are nouns.

Word	Noun	Adjective	Verb	Adverb
veggie	Yes	No	No	No
greens	Yes	No	No	No

As nouns, greens is a hyponym of veggie; that is, greens is a word with a more specific, narrower meaning than veggie:

veggie: edible seeds or roots or stems or leaves or bulbs or tubers or nonsweet fruits of any of numerous herbaceous plant
greens: any of various leafy plants or their leaves and stems eaten as vegetables

veggie (noun)	greens (noun)
edible seeds or roots or stems or leaves or bulbs or tubers or nonsweet fruits of any of numerous herbaceous plant	any of various leafy plants or their leaves and stems eaten as vegetables