Here’s why it matters: knowing the difference makes you a better drink maker. If you’re mixing a vodka soda, seltzer gives you a clean, sharp bite. If you’re making a highball or a classic gin and tonic (with club soda instead of tonic), club soda’s minerals can soften the alcohol’s burn. It’s a tiny tweak, but it changes the whole experience.
Plus, if you’re watching your sodium intake, seltzer is the winner—it usually has zero sodium, while club soda can have small amounts (usually 10–30 mg per can). Not a huge deal, but good to know if you’re counting.
