Bongs are different from other smoking apparatus like water pipes in the sense of the feeling. While using a bong the smoke passes through water very fast and you will feel it hitting your lungs straight away.
Bongs are sealed chambers which are half filled with water. These are fitted with a pipe which has a bowl in the end which leads to the chamber till the level of the water. There is another pipe which has a mouthpiece and enters the chamber above the water level. When the tobacco in the bowl is lit and is sucked through the mouthpiece the air pressure in the chamber gets lowered, as a result of which air travels from the bowl into the chamber and then into your lungs.