roach vs Rutilus rutilus

roach and Rutilus rutilus both are nouns.

Word	Noun	Adjective	Verb	Adverb
roach	Yes	No	Yes	No
Rutilus rutilus	Yes	No	No	No

As nouns, roach and Rutilus rutilus are synonyms defined as:

roach and Rutilus rutilus: European freshwater food fish having a greenish back

roach (noun)	Rutilus rutilus (noun)
any of numerous chiefly nocturnal insects; some are domestic pests	European freshwater food fish having a greenish back
European freshwater food fish having a greenish back
the butt of a marijuana cigarette
street names for flunitrazepam
a roll of hair brushed back from the forehead

roach (verb)	Rutilus rutilus (verb)
cut the mane off (a horse)
comb (hair) into a roach