There are a few ways to determine which Xbox 360 you have. The easiest way is to look at the console itself. On the front of the console, below the disc tray, you will see a label that has the model number of your console. If you don't have the console in front of you, or you want to verify the model number, you can check on Microsoft's website. They have a list of all the Xbox 360 models and their corresponding model numbers.