Dry skin is a skin type that is inherited via your genetics. Your skin lacks oil. It is pretty easy to identify. People with dry skin often feel tight and dry, no oil to be seen at all. The dryness might get worse and it fluctuates based on the climate, season, or activity, but regardless of those things, without great skincare products, the uncomfortable dry, tight feeling will continue.
The dehydrated skin is a skin condition that comes and goes, it does not carry on. Your skin just lacks water. People with dehydrated skin can look and feel like dry skin all over their face. Dehydrated skin can be seen clearly because of the amount of oil on skin’s surface. Regardless of this excess oil flowing through the pores all over the face, dehydrated skin people skin normally feels tight or dry everywhere on their face and that can be called as flaky skin.
Source: Eminence Blog and Paula’s Choice