Stock is made by simmering bones in water and is used to provide rounder and thicker mouthfeel, while broth is made by simmering meat and is used to provide flavor. The main factors that separate stock from broth are the ingredients, seasonings, and cook time. Although many chefs cook with broth and stock similarly, they do lead to slightly different results and perform best when used appropriately.
Stock is a liquid flavoring base that is commonly made from chicken or beef bones, however, pork or fish bones may be used as well. A prolonged simmering of the bones allows for the collagen and marrow to be released, which creates a thicker and slightly gelatinous texture while providing a fuller and richer mouthfeel. Stocks are left unseasoned to allow the chef control over the flavors in their dishes.