subclass Rosidae vs class Dicotyledones

subclass Rosidae and class Dicotyledones both are nouns.

Word	Noun	Adjective	Verb	Adverb
subclass Rosidae	Yes	No	No	No
class Dicotyledones	Yes	No	No	No

subclass Rosidae (noun)	class Dicotyledones (noun)
a group of trees and shrubs and herbs mostly with polypetalous flowers; contains 108 families including Rosaceae, Crassulaceae, Myrtaceae, Melastomaceae, Euphorbiaceae, Umbelliferae	comprising seed plants that produce an embryo with paired cotyledons and net-veined leaves; divided into six (not always well distinguished) subclasses (or superorders): Magnoliidae and Hamamelidae (considered primitive), Caryophyllidae (an early and distinctive offshoot), and three more or less advanced groups: Dilleniidae, Rosidae, Asteridae