I am looking for a concise wording that I can use to differentiate between mold and mildew.
Any thoughts? 
Refer to them as suspected micro organisms. Same thing on different surfaces. Can only be confirmed by testing.
In common usage, the terms “mildew” and “mold” are for the most part interchangeable. In some cases they are used in the same phrase: “mold and mildew”. The terms are used to describe the physical appearance of common fungi seen growing on objects both inside and outside buildings. This includes solid surfaces such as walls, floors, ceilings, as well as fruits and vegetables (fruits and vegetables are usually referred to as “moldy”). Moldshower curtain or bathtub is generally referred to as “mildew” (note the contextual use of the term) growing on a
Mildew IS a variety of Mold
Mildew IS a strand of Mold. Mildew is MOLD with a publicist.
It is all organic substances. The name of the particular substance is the only way I see to differentiate between them, and a lab has to do that.
What are you trying to do Bill? Break down between the bad and not so bad stuff?
I think Mike is correct;
Definition of Mold
Mold: A very large group of microscopic fungi that live on plant or animal matter. Most are filamentous organisms and produce spores that can be air-, water-, or insect-borne. A common trigger for allergies.
For people who are sensitive to molds, exposure can cause symptoms such as nasal stuffiness, eye irritation, or wheezing. People with serious allergies to molds may have more severe reactions. Severe reactions may occur among workers exposed to large amounts of molds in occupational settings, such as farmers working around moldy hay. Severe reactions may include fever and shortness of breath. People with chronic illnesses, such as obstructive lung disease, may develop mold infections in their lungs. People allergic to molds should avoid areas that are likely to have mold, such as compost piles, cut grass, and wooded areas. Mold growth in the home can be slowed by keeping humidity levels below 50% and ventilating showers and cooking areas. Mold growth can be removed with commercial products or a weak bleach solution (1 cup of bleach in 1 gallon of water). In situations where mold exposure is unavoidable, sensitive people should wear a tight-fitting face mask.
Definition of Mildew
A superficial coating or discoloration of organic materials, such as cloth, paper, or leather, caused by fungi, especially under damp conditions.
Marcel
Excellent posts - thanks to all of you.
Marcel - you hit the nail on the head. That was exactly what I was looking for.
I don’t know the difference or if there even is one, but Prolab does, and they’ll be glad to make all of us money to explain it.