Final answer:
Collusion involves agreements among firms to restrict competition and is illegal under antitrust law. Cartels are a formal type of collusion, but both explicit and tacit collusion can be difficult to prove, complicating enforcement efforts in the U.S.
Step-by-step explanation:
The key difference between collusion and non-collusion involves the nature and evidence of cooperative behavior among firms. Collusion refers to agreements or arrangements, either explicit or tacit, between competing firms to limit competition and maximize profits. Cartels represent a formalized structure of collusion, where firms explicitly agree on prices, market shares or production quotas. In the United States, both collusion and forming cartels are considered anti-competitive behaviors and are illegal under antitrust laws. Enforcement agencies like the Antitrust Division of the Justice Department and the Federal Trade Commission are tasked with preventing such practices. However, enforcing these laws can be challenging due to the difficulty of finding hard evidence of collusion, especially when it is tacit, as firms may not communicate directly but understand that competition could harm their profits.