Answer: Serums are very thin liquids made of water and silicones. They are especially effective vechicles for water soluable ingredients like vitamins E and B6. Serums mix well with natural skin oils and work beautifully under make-up. Lotions are water in oil emulsions which can deliver moisturizing incredients like ceramides and glycolic acid. Creams are thick oil-in-water emulsions that have the highest fat content of all combination products. Many have mineral oiland/or lanolin which make them excellent for very dry skin– less so for oily sensitive or acne-prone skin.