You can tell if your Cocker Spaniel is English or American by looking at their physical features: English Cocker Spaniels generally have a stockier build, a broader head, and longer ears, while American Cocker Spaniels have a more rounded head, a shorter muzzle, and a fluffier coat, especially around the chest and legs. Additionally, their size differs, with American Cockers being smaller and more compact compared to the slightly larger English variety.