Mildew is a type of mold that usually appears as a fuzzy, gray, or white growth on the surface of materials like wood. It is typically more superficial than other types of mold and is often caused by moisture or high humidity. Mold, on the other hand, is a broader term that can refer to any type of fungal growth. Mold can appear in a variety of colors, including black, green, white, and orange, and often penetrates deep into the wood as compared to mildew. It is typically slimy in appearance and is caused by dampness or moisture, as well as poor ventilation. Both mildew and mold can pose serious health risks due to long exposure, so it is important to take action as soon as possible to remove the growth and prevent it from returning. While mildew may start white or gray if left untreated, it may turn black in color, which may perhaps cause some confusion as to if what you’re seeing is mold or dirt; during such a case, you may conduct a simple test to figure things out. Simply rub the mold with a little bit of non-chlorine bleach; if the stain disappears, then it is most likely mildew; if the stain lightens but does not go away, then you’re likely to be dealing with dirt.