English Cocker Spaniel are english and American Cockers are american

Both breeds have the same purpose and function. English cockers a lareger, have a longer face, and a more "natural" look. American cockers are more flashy then their english counter parts, which is typical for any american bred dog/breed. The American is also smaller, has ashorter face, and a more sloped back. The american is a decendent of the english and over time has been developed into the english Cocker Spaniel. Think of it as the amerian bred GSD's being a different breed from the euorpean GDS's.