Up in Maine, clams is the "Steamahs" which are the ong necked variety. Quahogs (CO' hogs) are what, in New Jersey and Tidewater states we all call
Little necks, or cherrystones, Top necks or Chowderclams (also known as piss clams).
We southerners mostly eat the clams of the genus Mercenaria while New ENglanders eat the genera Mya and Macoma (although the ranges of these clams overlap, each is more common in their geographic ranges since New ENgand clams tend to be long siphoned "desmodontia" types).
I remember once lecturing some student kids over clams and beer when I burped out the entire word Demosdontia and thus acquired a whole new enhanced status among my students.