There is not much difference in principle. Water drives the rotor to rotate to generate electricity. Generally speaking, hydropower uses the height difference of reservoir water level to generate electricity, which requires a larger device. The tap water pipe is very thin and the equipment is very small. I'm afraid the difference between the two is not a little bit from the technical details. As far as I know, hydropower technology is mature. If hydropower technology is used for reference to tap water power generation, it is at best a new practical technology, not an invention.
Moreover, from the perspective of energy conservation, the water pressure in the water supply pipe is obtained by human consumption of energy. Installing a device on the water supply pipe will definitely lose some water pressure, that is, the energy of the water supply company. The most ideal thing is to transform the energy of the water supply company into its own electricity without loss, and at the same time sacrifice its own water pressure. The energy of the whole society has not increased or been saved.