quahog vs Mercenaria mercenaria

quahog and Mercenaria mercenaria both are nouns.

Word	Noun	Adjective	Verb	Adverb
quahog	Yes	No	No	No
Mercenaria mercenaria	Yes	No	No	No

As nouns, quahog and Mercenaria mercenaria are synonyms defined as:

quahog and Mercenaria mercenaria: an edible American clam; the heavy shells were used as money by some American Indians

Other synonyms of quahog include hard-shell clam, hard clam, quahaug, round clam, Venus mercenaria.

quahog (noun)	Mercenaria mercenaria (noun)
an edible American clam; the heavy shells were used as money by some American Indians	an edible American clam; the heavy shells were used as money by some American Indians
Atlantic coast round clams with hard shells; large clams usually used for chowders or other clam dishes