Explain to me what the difference is? You can lock.a fob away and lock the car with your watch surely. The new activity key is just a watch app now anyway at more than twice the price of a far better and more functional watch.Yes, you can lock/unlock the car via phone apps (Jaguar app, WattCat, etc.) or watches running apps as you point out.
This thread is about the activity key. The activity key's purpose is to allow locking/unlocking while leaving an authorized fob inside the car while the driver goes off and does some other activity.