genus Carduus vs Compositae

genus Carduus and Compositae both are nouns.

Word	Noun	Adjective	Verb	Adverb
genus Carduus	Yes	No	No	No
Compositae	Yes	No	No	No

genus Carduus (noun)	Compositae (noun)
genus of annual or perennial Old World prickly thistles	plants with heads composed of many florets: aster, daisy, dandelion, goldenrod, marigold, lettuces, ragweed, sunflower, thistle, zinnia