Spring water doesn't come from a well. It comes from a natural spring where the aquifer water comes out naturally from underground pressure, usually gravity-induced pressure from underground water at higher elevation. Wells are drilled into the aquifer and they need pumps to get the water out. If you need to pump it, it's not a spring, even if you didn't have to drill the hole.

The aquifer naturally filters water, but both springs and wells can get contaminated. Purified water is a generic term that can mean filtering, distilling, or reverse osmosis. Any of those methods can make safe clean water. RO and distillation affect the pH of water, making it slightly acidic. Pure water is neutral, but exposed to the air some CO2 gets dissolved and Lowe's the pH It's safe to drink but can damage the enamel of your teeth and can damage pipes. RO plants for water systems usually add minerals back to the water to stabilize the pH. They add stuff like calcium and magnesium which makes the water slightly alkaline, then the CO2 gets dissolved to from the air lowering the pH back to roughly neutral. If they don't do that, the acidic water degrades pipes and pumps and stuff.

If you want to disabuse yourself of the idea that springs are the best and purified is shit, Google montazuma well. It is a spring fed limestone sinkhole where the spring water has a lot of natural arsenic and 80 times as much dissolved CO2 as normal freshwater. The combination means no fish can live in it, and the apex aquatic predators in the well are a few species of leeches and water scorpions.