Volts: Water pressure. The higher the pressure, the more forceful it goes through, but you can have a large or small diameter pipe with high and low pressures. But water can be highly pressurized without actually moving.

Amps: Water flow rate. More amps means more water flowing through the pipe, per second.

Watts: Power of the water. Multiply the pressure by the flow rate to get this. Higher with more water flow (amps) and higher pressure (volts).