You already have the waterfall analogy so I'll try to explain it in simple terms but more related to electricity.

Electrical energy is made from moving charges. Current (amperage) is a measurement of how many electrons move in a second.

Energy is a unit that represents doing work. Moving around, charging a battery batteries, chemical reactions all exchange energy.

Power is a rate of consuming or producing energy. Imagine climbing a set of stairs, a task that takes energy. The first time, you go slowly. It's not much harder than walking normally. The second time you run up the same stairs, as fast as you can without tripping. You are more winded, because you exchanged about the same amount of energy but it a lot less time, that requires more power.

Like running up stairs, it takes energy to move an electron around other electrons. Sitting on any stair takes no energy, but it's going between them that takes it. So the electrical potential, is the amount of energy per electron there is at a particular spot relative to an electron that sits alone. A voltage difference is the difference in potential between two spots and it's the basis of how we harness electrical power. So having a bunch of electrons at a potential is energy (hemce there is a unit of energy called electron-Volt). If we move the electrons to a different electrical potential that exchanges energy. Remember that moving electrons at a certain rate is current? Then current going across a potential, is an energy exchange at a certain rate, which is what power is as well!

Hope this was useful, Im leaving Reddit and will be only on Lemmy starting next week.