Cosmetics are the creams, powders, lipstick, mascara and so on that people put on the face — and sometimes the body — to look more attractive or to change how they look. Makeup is the everyday word for the colour products (lipstick, eyeshadow). Cosmetics is the wider shop-and-label word: a cosmetics counter may sell colour and also skin cream. It is a neutral word, not slang and not especially stiff. You will see it on signs, packets, and in more careful writing. Though actually, the related adjective cosmetic is where English stretches: a cosmetic change is a change that only tidies the surface and does not fix the real problem. That stretch belongs more to cosmetic than to the noun cosmetics, but you will hear it.