How is carpet steam cleaning different from carpet dry cleaning?

Carpet steam cleaning refers to a process that involves hot water extraction technique. Hot water is injected into carpet using high pressure and then the water is extracted out. With the water extraction, all the dirt and other contaminants are extracted along leaving the carpet clean. The stains are pre-treated with effective cleaning agents and sometimes a pre-spray is used before injecting water to ensure it reaches to the deepest parts.
For carpet dry cleaning, first of all vacuum is used to remove the outer dry soil particles. The carpet dry cleaning solution is used that breaks down the oil in the carpet. Then hot water cotton absorbent pads are used with the help of a rotary machine to polish the carpets. These spinning pads get rid of dirt and other contaminants from the carpets.
Different carpets need different cleaning methods and for very dirty carpets, sometimes even a combination of both carpet steam cleaning and dry cleaning is advised.