What's the difference between a nanofiltration water purifier and a water purifier?

They all belong to water purifiers, but their functions are different and the final water quality is different. The water purifier filters everything, including harmful and beneficial minerals. The nanofiltration water purifier filters out harmful substances and leaves beneficial mineral water. I suggest that if there are old people and children at home, drink more mineral water, which is good for both old people and children.