New England Clam Chowder and Boston Clam Chowder are the same thing except for the broth that is used to make the clam chowder.
One broth is thicker than the other.
Boston Clam Chowder has a thicker creamier broth while New England Clam Chowder has a thinner less thick and less creamy broth to it.
They taste pretty similar because they're nearly the same but one is creamier and thicker than the other.