Water with high hardness and high TDS levels responds well to RO water filtration technologies. It's the only method of purification that softens and enhances the flavor of cleansed water. You could taste a difference and favor one over the other. Pure water is, in essence, pure water. Distillation produces pure water by condensing boiling water vapor, whereas reverse osmosis produces pure water by forcing water to flow through a semipermeable membrane.