There are a lot of differences between THE DOG Island and THE CAT Island.
Like in the game Catz, instead of Sniffing you use Whiskers Radar. Therefore, you are training to be a Whiskers Master. Tao will send you to find the First Book of the Whiskers Master, Second Book of the Whiskers Master, and the Whiskers Master Medal.
In THE DOG Island, you recieve Woofs for helping out the other dogs. They are used for buying items and travelling around the island with Boris. In THE CAT Island, you do not recieve Woofs, but instead recieve Meows.