CLub Soda and Seltzer water...why both?

At my Safeway and others, they carry both Club Soda and Seltzer Water. Now I know the difference between the two is that Club Soda has a trace amount of salt in it, even though both products list their sole ingredient as “Carbonated Water”. My question is Why do they manufacture and sell two nearly identical products? Is there a use or recipe for one product that just won’t work if the other is used? If I accidently buy Seltzer water instead of Club Soda, will it not take that stain out of my carpet? And if I buy club Soda will its added trace of salt provoke heart attacks in the hypertension-enhanced American population? Help me understand this!

I did an extensive Google search and found this very good explanation (middle of page) of the difference which matches well with what you wrote. For the search I plugged “club soda seltzer water difference” into the search engine. I couldn’t find a cite which said that the two couldn’t be used interchageably for either recipes (food or beverage) or cleaning solutions. I suppose that one who is extremely intolerant to salt may want to stick with Seltzer water. They have to be called by different names due to arcane food labeling laws in the U.S.