Let’s start with the obvious. The Maltese is a purebred dog and the Maltipoo is a hybrid dog. In order for a dog to be considered 'purebred' he must be a descendant of known purebreds of the same breed. Most purebred dogs are registered with a kennel club, but it is not required. The clubs were created to keep a guideline that dictates the expected size of the dog, coloring, ear set, tail set etc.. This helps keep a consistent appearance within the breed.