http://www.aehf.com/articles/molds.htmlMold, mildew, and fungi are all terms generally used to describe a distinct group of organisms that appear as wooly or powdery growth. Although often used interchangeably, these terms, in fact, are not synonymous. Rather, mold and mildew (along with rusts, yeasts, and mushrooms) are different members of the fungus family. Although once considered a part of the plant kingdom, fungi are now regarded as a distinct kingdom of organisms.
Although distinctly different entities, mold and mildew are similar in structure. Mold grows on surfaces in masses of branching threads that resemble dense cobwebs, and individually these fertile threads can produce hundreds of thousands of spores in four to nine days. These spores then move about via air currents or by adhering to insects or animals or water. Although omnipresent and able to form new colonies wherever they land, spores of different mold species seem actually to be quite fussy about where they will and will not grow. The green mold that grows on an orange, for instance, will not grow on an apple or a damp carpet or in a human lung. Active mold can be any color, depending on its species and the substance on which it is growing.