quahog vs hard clam

quahog and hard clam both are nouns.

Word	Noun	Adjective	Verb	Adverb
quahog	Yes	No	No	No
hard clam	Yes	No	No	No

As nouns, quahog and hard clam are synonyms defined as:

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

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

quahog (noun)	hard clam (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