What is the difference between dandruff and dry skin?

They can look alike: They can look the same on the scalp, however there can be subtle differences. Dry skin would tend to be over the entire scalp and can worsen with use of a medicated shampoo. Gentle shampoos and less frequent washing are better for dry scalp. Dandruff is usually from psoriasis or seborrheic dermatitis on the scalp, often with thicker, larger scales, redness, itching. Medicated shampoos often help.