[atishay811]

For the Corolla vs Corvette example, Toyota allows you to open the hood and take the toyota engine out. The screws are all standards and tools are available to get parts you need to take the engine out. If you had the tools to fit the Corvette engine in place, you are allowed to do it. You could build your own custom engine as well and put it there. We can put a lot of after market stuff in our cars, replace tires, wheels or even engine if we want to. WE own the car fully.

With the App Store case, they don't allow you to open the hood, unscrew and take out the apple app store and put an alternate app store. While Jailbreaking is legal, you need to use a hack to open up your iPhone and Apple actively plugs those holes in the next versions.