Here's an excellent description of the difference between the Cavalier King Charles Spaniel and the King Charles Spaniel (known as the English Toy Spaniel in North America):
http://www.cavaliers.co.uk/articles/difference kcs v ckcs.htm
Also, see: http://www.kingcharles.se
http://www.cavaliers.co.uk/articles/difference kcs v ckcs.htm
Also, see: http://www.kingcharles.se