My take on stock and broth comes from teh words used to label each. Stock is the basic flavored liquid made from bones and meat. It is used to stock the shelves with a product that can be used for many recipes. it it is usually made from roasted or leftover bones that still have meat, connecting tissue, and cartilage on them. The bones are often fractured or broken to expose the bone marrow to the braising process. The marrow, fat, connecting tissue, and any gristle or cartilage breaks down into a liquid and adds flavor, nutritional value, and texture to the stock. The meat helps flavor it. The only seasoning in a stock is usually salt. The stock can be used to make anything from demi glace to beef 7 barley soup.
Broth is a stock that has been fortified with the flavors of vegetables, usualy at least carrot, celery, and onion. Herbs and spices can also be added to obtain the desired flavor you want. Broths are often part of soup recipes, and can also be used to make gravies, or combined with a roux to make an espanole sauce. You could state that a broth is a daughter sauce of a good stock.
In poultry, and some other meats, the skin will add flavor and collagen to the stock. Stocks can often be started from pan drippings, as from a roasted chicken or turkey, or pot roast. You can even use the fond from a pan of fried mead, as long as there isn't too much fat.
If the stock is made from fish, it is called a fume'.
Hope that helps.
Seeeeeeeya; Chief Longwind of the North