The truth is, water is water. The only differences between the types of bottled waters is where its source is and what processes the water undergoes before it is bottled. Mineral water and spring water are two common types of bottled water.
Mineral Water
Mineral water can come from a natural well or from a spring, but it must contain no less than 250 parts per million of trace minerals. These minerals, such as calcium and magnesium, are good for a person's health, and manually added to the water. Due to the strict requirements for what makes bottled water, the number of water sources where this type of water can come from is extremely limited. Mineral water mostly comes from Europe, and is therefore generally more expensive outside of the European Union. Some find mineral water to be harsher tasting than other types of water due to the minerals present, so many bottlers offer flavored varieties of the water type.
Spring Water
Spring water comes from natural aquifers located around rockbeds and soil. Water that comes naturally to the surface from under ground and has no natural tributaries is considered spring water. Spring water is naturally rich in trace minerals, and some municipalities use spring water as their tap water. Sometimes the water is processed with chemicals and advanced filtration systems before being sold. The water is considered to be among the best overall types of water for its health benefits and rehydration, and is fairly inexpensive.
One and the Same
Spring water can be considered mineral water if it naturally contains the required amount of trace minerals. Mineral water can be spring water if it comes from an underground aquifer from which water flows naturally to the surface. While spring water refers to where water comes from, mineral water refers to what the water contains.