Dry skin is caused by low levels of oil on skin, dehydrated skin means there’s not enough water. So your skin can be dehydrated while still having plenty of oil, or it can be both dehydrated and dry at the same time.Hydration are used to the water content within the cells that leads them to swell and be plump and bouncy, thus reflecting light well. If water flows out of the cells and the cells are dehydrated, they can become shriveled, which leads to lackluster skin,”. When you’re using a topical hydrator, you’re infusing your cells with water and improving your skin’s ability to absorb moisture and nutrients.