Rattus norvegicus vs brown rat

Rattus norvegicus and brown rat both are nouns.

Word	Noun	Adjective	Verb	Adverb
Rattus norvegicus	Yes	No	No	No
brown rat	Yes	No	No	No

As nouns, Rattus norvegicus and brown rat are synonyms defined as:

Rattus norvegicus and brown rat: common domestic rat; serious pest worldwide

Other synonyms of Rattus norvegicus include Norway rat.

Rattus norvegicus (noun)	brown rat (noun)
common domestic rat; serious pest worldwide	common domestic rat; serious pest worldwide