Mildew is generally white or grey, and mold is black or green. Mold normally grows on food, and mildew grows on damp surfaces. Mildew has a flat growth, while mold has a multicellular or complex form.
Although mildew and mold are both kinds of fungi, mildew is commonly referred to as a type of mold. Mildew has a powdery appearance, and mold has a fuzzy appearance. Mold causes structural damage to buildings and can cause severe health issues, especially in people with allergies and asthma. In the case of toxic mold, lung issues, irritated eyes and headaches can develop, according to HGTV. Mildew causes damage to fabrics or crops and can also be hazardous to a person's health. Mold and mildew can cause respiratory problems, headaches and allergic reactions, among other ailments.