What are the key differences between perfect competition in the short run and long run?

In perfect competition, the key differences between the short run and long run are mainly related to the ability of firms to adjust their production levels and make profits. In the short run, firms cannot easily enter or exit the market, leading to potential economic profits or losses. In the long run, firms can enter or exit the market, driving profits to zero as competition increases. This results in a more efficient allocation of resources in the long run compared to the short run.