Okay, so I don ' t have any real specs but i just want to know how big is the difference between water from tap versus the one from fire hose versus the pressure washer?
You can get started on this calculation on your own. Make reasonable estimates of the diameter of the stream and how much water is moved per second; from that you can get the speed of the water in the stream. Now you can use the definitions of kinetic energy and power to get answers about as good as your original estimates.