First, the simple truth: both are just water with carbonation. But that's like saying a cupcake and a muffin are the same. They are not.
Seltzer water is the purest sparkler. It's plain water injected with carbon dioxide gas. That's it. No extras, no attitude. It's the minimalist of the fizzy world.
Club soda, on the other hand, is a show-off. It starts with carbonated water, but then adds tiny amounts of minerals. Think sodium bicarbonate, potassium sulfate, or sodium chloride. Fancy, right?
These minerals aren't for flavor—they mimic natural spring water. They also give club soda a slightly salty, crisp bite. Seltzer is just neutral and clean.
