Distilled water and demineralized water are both types of purified water, but they are made with different processes. Distilled water is heated above the boiling point to become water vapor. The vapor is collected in a separate container, leaving the impurities behind. The vapor returns to liquid as distilled water.
Demineralized water is made by passing water through ion exchange resins. The water exchanges contaminating anions and cations with hydrogen and hydroxide, which combine to form water. Both types of water meet international quality standards, but demineralized water is cheaper than distilled water. Demineralized water can be used for most of the same things as distilled water, except in some situations such as lead-acid batteries in vehicles or the enameling industry, in some laboratories, and as a coolant for nuclear-reactors in ships and submarines.