well you see, the engine of a car turns gasoline into "motion" usually by burning it and causing "combustion"
the principle is that if you put something with lots of energy in a teeny tiny living space, the energy released will be that much greater. (sucking through a tight straw is easier than a big straw)
essentially inside the car, it lets gasoline in a small tank, where a piston forces it in a tiny space, which ignites the gasoline, pushing the piston down, and propels the car and releases exhaust.
nuclear reactors just use its nuclear heat to turn water into vapor and uses that vapor to spin turbines
and creates electricity.
Eh, not really. An engine works by spraying a small amount of gasoline into a chamber (piston) with air, which is then compressed by the centrifugal motion of the camshaft forcing the piston down. Once the piston has compressed the gasoline/air mixture as much as it can, a unit called a spark plug proceeds to ignite this fuel causing an explosion. The force of this explosion shoots the piston upwards, which is connected to the cam shaft and causes the cam shaft to spin, both forcing more pistons down and causing rotational velocity to use to be propelled.
A nuclear reactor is a bit different, the reactor shoots neutrons into fissile material (usually an unstable isotope of uranium) which causes the unstable isotope of uranium to break down into a different element, shooting out extremely high-energy gamma radiation. This process causes further instability in surrounding atoms, creating a chain reaction of decay. To control the rate of decay, there are control rods that absorb neutrons in the reactor that slow the rate of reaction. These rods can be raised or lowered into the reactor to dampen or increase the speed of reaction. Anyway, since this chain reaction causes a great deal of high-energy particles to be emitted from the core, water surrounds the core for two purposes: to cool the reactor and to vaporize into steam. Without the cooling effects of water, the nuclear reactor would overheat and go into what's called a meltdown-- when the extremely hot runaway reaction literally melts through the reactor down into the earth below it, unable to be stopped. Anyway, the boiled water obeys the "heat rises" rule and can be used to spin turbines with this upward force. These turbines spin coils around a gigantic electromagnet, creating current in the coils and thus electricity.
And that concludes Engineering and Nuclear Physics class today kids, don't try either at home!