Molds and mildew are both types of fungi—but that is often where the similarities end. They differ in color: the molds are usually black, red, blue, or green; mildew is usually gray or white. Molds are most often slimy and fuzzy; mildew is typically powdery. Mold grows as multifilament hyphae, while mildew grows flat. Molds are usually found on rotted food, ceilings, and walls. Mildew is most often found in showers, bathtubs, and sinks—and even plants; it comes as powdery and downy. But both grow in any place in which damp, humid conditions exist.
If you find something dark and fuzzy growing on food, it is probably mold, not mildew.