bok choy vs cruciferous plant

bok choy and cruciferous plant both are nouns.

Word	Noun	Adjective	Verb	Adverb
bok choy	Yes	No	No	No
cruciferous plant	Yes	No	No	No

As nouns, cruciferous plant is a hypernym of bok choy; that is, cruciferous plant is a word with a broader meaning than bok choy:

bok choy: Asiatic plant grown for its cluster of edible white stalks with dark green leaves
cruciferous plant: any of various plants of the family Cruciferae

Other hypernyms of bok choy include crucifer.

bok choy (noun)	cruciferous plant (noun)
elongated head of dark green leaves on thick white stalks	any of various plants of the family Cruciferae
Asiatic plant grown for its cluster of edible white stalks with dark green leaves