Sparkling water and club soda are both examples of carbonated water. Carbonated water is water that is infused with carbon dioxide, which creates an aerated, bubbly liquid.
The first human-made carbonated water was produced by British scientist and inventor Joseph Priestly in the 18th century. It is also possible for carbonated water to occur in the Earth naturally.
Sparkling water, which can be produced naturally or by adding carbon dioxide to water, contains no other ingredients. Flavoring may be added, but the foundation is simply carbonated water.
Club soda is produced in a slightly different fashion from sparkling water. Traditionally, club soda contains a small amount of salt; however, commercial club soda producers may also add ingredients such as sodium bicarbonate, sodium citrate, and potassium carbonate or sulfate.
Sparkling water that is carbonated naturally, or in the Earth, results from water that is affected by unusual geological conditions, generally related to volcanic activity or volcanic gases. Club soda is always produced artificially.
When mixing drinks, club soda and sparkling water are often interchangeable, and much depends on personal preference or availability. In some cases, a drink's quality will depend on the strength and slight saltiness of club soda or the smooth fizziness of sparkling water.