The pistons in a car engine are responsible for converting the energy generated by the combustion of fuel into the mechanical motion that turns the wheels of the car. This happens through a series of coordinated movements that begin with the spark plug igniting the fuel. The resulting explosion creates a wave of force that pushes the piston down in the cylinder, which in turn drives the crankshaft and ultimately, the wheels.

The carburetor, on the other hand, is responsible for mixing fuel and air in the correct proportions, so that the engine can run smoothly and efficiently. It does this by using a series of valves and jets, which work together to let in the right amount of air and fuel, and then mix them together in a precise and controlled manner. This ensures that the engine gets the right amount of fuel to power it, without wasting any or producing harmful emissions.