As you can see, the overall outside appearance of a liquid fuel rocket is almost exactly the same as that of a solid fuel rocket, but the workings on the inside are quite different.

     The first difference is the lack of solid fuel boosters, and the appearance of large tanks filled with various substances.  In this case the diagram on the left has a ratio of two to one between the oxidizer and the propellant, and the pressurant is approximately at a one to three ratio to the oxidizer.

     All of these ratios go together to make the most efficient reactions possible.

	The number one is the oxidizer pump: this makes sure that just the right amount of oxidizer flows into the combustion area at the base of the rocket.
	The number two is the pressurant pump.  This makes it possible to keep the liquid oxidizer from turning into a gas before it is ready for combustion, and the liquid fuel as well.  Also, the pressurant can be ejected directly into the combustion chamber to keep unsafe temperatures in check.
	Number three is the fuel pump.  This is to control the amount of thrust that is leaving the rocket, thus controlling the speed, and the acceleration.