 King Charles Spaniels are often mistaken for Cavalier King Charles Spaniels . There are several significant differences between the two breeds , the principal being the size . While the Cavalier weighs on average between 13 to 18 pounds ( 5 @.@ 9 to 8 @.@ 2 kg ) , the King Charles is smaller at 8 to 14 pounds ( 3 @.@ 6 to 6 @.@ 4 kg ) . In addition , their facial features , while similar , are distinguishable : the Cavalier 's ears are set higher and its skull is flat , while the King Charles ' is domed . Finally , the muzzle length of the King Charles tends to be shorter than the typical muzzle on a Cavalier . 
