The Cavalier King Charles Spaniel is a breed on its own and is known for its friendly and affectionate nature. It typically has a slightly longer nose and a flat or slightly rounded head.

On the other hand, the King Charles Spaniel, also known as the English Toy Spaniel, is a separate breed. It has a distinctive domed head and a flat face. This breed was historically favored by royalty and is known for its elegant and regal appearance.