A little bit of basic:

Kilowatts (KW) are the amount of power you are using at any instant of time. A horsepower is roughly 760 Watts, or 0.76 KW. Yes, if you have a 200 horsepower automobile you have the ability to generate 152 KW

A typical house gets by on roughly 5KW on average. This allows for averaging out your electric cooking load and night-time lights out but not your home lathe nor sauna.

Kilowatt HOURS is what you pay your electric utility for, measured by a meter at your domicile.

So, if you analogize electricity as a flow of (current) past or through a point (where your electric devices are), you might tap a lot of flow for a small amount of time, or a little flow for a long time. Imagine the water filling a basin. You're paying for the amount of water you've used.

As a rule of thumb, using electricity as a heat source costs the most. This includes air conditioners which pump heat outside your house in the summer. This includes your refrigerator and your electric clothes dryer. Using electricity for music or lighting is a lower level of use. Using electricity for your computer is in this middle area. Note that the high performance computers and CPUs and cathode ray monitors are running hotter, requiring cooling, etc. Your laptop uses a high efficiency CPU which may run slower or be able to turn itself off, and an LED screen. This uses a fraction of the power as your desktop tower monitor. (I use a low power unit for my internet use, so I don't use much more than a laptop).

The lowest level is the small amount of power required in the thermocouples of your water heater and gas stoves, wired-in smoke and CO detectors, and night lights. Think of it like:

Heaters and air conditioners: 1000's of watts
Computers, hifis, TVs:       100's of watts
Night lights, background use: 10's of watts

Pretty much anything that plugs in has information stamped on it telling you how much wattage it requires.

When I worked for the state our rule of thumb was that if you buy your own generator and fuel it and use that power you'll pay about half a buck for each Kilowatt Hour. Across the US i've seen rates from 5 cents to 15 cents per KWH.

Getting back to cars for the moment: If you wanted an electric car to take the place of that 200 HP vehicle in the driveway, you would NOT be able to put a 200 HP electric motor in your car. Electric motors are way too heavy. But you don't need to, because of the way they work, electric motors generate much more torque than internal combustion engines, so for comparable performance you don't need comparable horsepower. A 100 horsepower electric motor will provide awesome vehicle performance but will still be very heavy.