What is the difference between Clam Chowder and New England style?
There are several major varieties of clam chowder, which you can find enumerated on the Wikipedia page. New England clam chowder is characterized by a dairy base, usually with some sort of salt pork or bacon, and potatoes.

Note:  the term chowder basically just means soup or stew, usually with seafood of some sort--very different dishes may go by the name.