Final answer:
Production functions differ among firms due to the product-specific nature of production and individual firm processes, labor requirements, and use of inputs like fixed resources which define their operational limitations.
Step-by-step explanation:
Production functions tend to differ from one firm to another because they are specific to the product and the particular processes each firm uses in manufacturing. For instance, the amount of labor and other inputs required for agricultural products, such as a bushel of wheat, will differ significantly from those needed to manufacture complex goods like automobiles. Even within the same industry, production functions can vary, as each firm may have its own method of production and set of efficiencies. A practical example is found in the pizza industry, where one restaurant may make its own dough and sauce requiring more labor, as opposed to another that purchases pre-made ingredients. Further, a sit-down pizza restaurant likely utilizes more labor for table service compared to a take-out establishment. Additionally, the concept of fixed inputs, like a building lease, can influence a firm's production function by defining its maximum output capacity, correlating with the broader economic concept of a society's production possibilities curve.