Final answer:
The long run is when all costs are variable, while the short run is a period of time when at least one cost is fixed. In the long run, firms have more flexibility to make changes to their production processes. The distinction between the short run and the long run is determined by the firm's ability to adjust factors of production.
Step-by-step explanation:
The long run is the period of time when all costs are variable. It depends on the specifics of the firm in question and varies for each business. In the long run, a firm has the flexibility to make changes in its production process such as building new factories, purchasing new machinery, or closing existing facilities.
The short run, on the other hand, is a period of time when at least one cost is fixed. In this period, firms are unable to adjust their usage of fixed inputs. The distinction between the short run and the long run is more technical and determined by the firm's ability to change the factors of production.