Soda water is one of the many terms for carbonated water. Other synonyms include club soda, sparkling water, seltzer, or fizzy water. Carbonated water has been around for several decades, and is credited in invention to two people, who independently invented processes for adding carbon dioxide to plain water.
I must be really thick because I never realised sparkling and soda water were the same - strange that - why sell them under different names then? I've never liked soda water - I must try it again! x