littleneck clam vs quahaug

littleneck clam and quahaug both are nouns.

Word	Noun	Adjective	Verb	Adverb
littleneck clam	Yes	No	No	No
quahaug	Yes	No	No	No

As nouns, quahaug is a hypernym of littleneck clam; that is, quahaug is a word with a broader meaning than littleneck clam:

littleneck clam: a young quahog
quahaug: an edible American clam; the heavy shells were used as money by some American Indians

Other hypernyms of littleneck clam include hard-shell clam, hard clam, Mercenaria mercenaria, quahog, round clam, Venus mercenaria.

As nouns, quahaug is a hypernym of littleneck clam; that is, quahaug is a word with a broader meaning than littleneck clam:

littleneck clam: a quahog when young and small; usually eaten raw; an important food popular in New York
quahaug: Atlantic coast round clams with hard shells; large clams usually used for chowders or other clam dishes

Other hypernyms of littleneck clam include hard-shell clam, quahog, round clam.

littleneck clam (noun)	quahaug (noun)
a young quahog	an edible American clam; the heavy shells were used as money by some American Indians
a quahog when young and small; usually eaten raw; an important food popular in New York	Atlantic coast round clams with hard shells; large clams usually used for chowders or other clam dishes