Technically, they are not exactly the same, but they are often used interchangeably in casual conversation. Toronto Island Park is an archipelago made up of several interconnected islands, and Centre Island is the most popular and central island within that park. Centre Island houses the famous Centreville Amusement Park, the Far Enough Farm, and the main ferry docks, making it the primary destination for most visitors. Other major parts of the island chain include Ward's Island (mostly residential) and Hanlan's Point (known for its beach and airport). So, while you are on a "Toronto Island" when you visit Centre Island, you are only visiting one specific part of the larger 15-island park system located just offshore from downtown Toronto.