Both ‘mold’ and ‘mildew’ are used generally to describe growths of fungi on various surfaces. And, no matter what the differences are, you should work to clean your home of both just to be on the safe side.
Differences between the two are (1) their appearance, and (2) the surfaces in which they are growing.
Mold is typically thick and can be black, green, or even blue in color. Both can be found in moist and warm locations, but mold favors your home’s walls as well as other permanent structures and features of the home.
Mildew is both a lighter color (think gray and white) as well as a lighter growth that isn’t as thick as mold tends to be. Mildew makes its own home in the showers and in the fabrics of yours.
To defeat each of these growths, be conscious of the moisture in your home and work to dry out the area as soon as you can!