What was the difference between foam system and ordinary firewater system to estinguish in case of a fire to a industrial plant?

Foam system for fighting petroleum fires such as fuel and oils.

Firewater system for fighting porosity materials such as woods, clothes, etc. 

A fire sprinkler system is an active fire protection measure, consisting of a water supply system, providing adequate pressure and flowrate to a water distribution piping system, onto which fire sprinklers are connected. Although historically only used in factories and large commercial buildings, systems for homes and small buildings are now available at a cost-effective price.[1] Fire sprinkler systems are extensively used worldwide, with over40 million sprinkler heads fitted each year. In buildings completely protected by fire sprinkler systems, over99% of fires were controlled by fire sprinklers alone