nightshade vs ligneous plant

nightshade and ligneous plant both are nouns.

Word	Noun	Adjective	Verb	Adverb
nightshade	Yes	No	No	No
ligneous plant	Yes	No	No	No

As nouns, ligneous plant is a hypernym of nightshade; that is, ligneous plant is a word with a broader meaning than nightshade:

nightshade: any of numerous shrubs or herbs or vines of the genus Solanum; most are poisonous though many bear edible fruit
ligneous plant: a plant having hard lignified tissues or woody parts especially stems

Other hypernyms of nightshade include woody plant.

nightshade (noun)	ligneous plant (noun)
any of numerous shrubs or herbs or vines of the genus Solanum; most are poisonous though many bear edible fruit	a plant having hard lignified tissues or woody parts especially stems