Dandruff in essence is a mild form of scalp seborrheic dermatitis. Both of these conditions leave the scalp itchy and dry. The noticeable difference is that dandruff is only seen on the scalp while seborrheic dermatitis is present on all oily areas like the face, upper chest, ears, and scalp. Dandruff is small, white, or yellow flakes spotted on the scalp or hair. Seborrheic dermatitis is a common kind of skin rash that appears as plaques of greasy, yellow scaly skin. Those with weakened immune systems or neurological conditions are at more risk of having Seborrhea.