Brassica oleracea vs crucifer

Brassica oleracea and crucifer both are nouns.

Word	Noun	Adjective	Verb	Adverb
Brassica oleracea	Yes	No	No	No
crucifer	Yes	No	No	No

As nouns, crucifer is a hypernym of Brassica oleracea; that is, crucifer is a word with a broader meaning than Brassica oleracea:

Brassica oleracea: wild original of cultivated cabbages; common in western coastal Europe
crucifer: any of various plants of the family Cruciferae

Other hypernyms of Brassica oleracea include cruciferous plant.

As nouns, crucifer is a hypernym of Brassica oleracea; that is, crucifer is a word with a broader meaning than Brassica oleracea:

Brassica oleracea: any of various cultivars of the genus Brassica oleracea grown for their edible leaves or flowers
crucifer: any of various plants of the family Cruciferae

Other hypernyms of Brassica oleracea include cruciferous plant.

Brassica oleracea (noun)	crucifer (noun)
wild original of cultivated cabbages; common in western coastal Europe	any of various plants of the family Cruciferae
any of various cultivars of the genus Brassica oleracea grown for their edible leaves or flowers