The Affen Spaniel is created by crossing the purebred Affenpinscher with the purebred Cocker Spaniel. It is considered a hybrid dog, meaning it is not purebred, however the lineage is known.
When a dog has an unknown lineage, then the proper term to call them is Mutts.
When two purebred dogs of different breeds are bred together, their offspring are more properly called hybrids or a hybrid breed.
However, these days both mutts and hybrids are often referred to as Designer Dog Breeds by pet shops and owners to make them sound more glamorous.