Mold and mildew are both fungi that grow in areas of warmth and moisture; however, they are dissimilar in several ways, including their colors and their growth patterns. Mildew tends to be white or gray and grow in small patches, while mold is black or green and can grow in large infestations and take on a slimy or fuzzy appearance.
Mildew is fairly easy to remove using a scrub brush and cleaner, while mold can be difficult to eradicate. Mildew usually doesn't cause health problems, while mold can pose a danger to health, especially in people with allergies and asthma. In the case of toxic mold, lung issues, irritated eyes and headaches can develop, according to HGTV.