Final answer:
Monopolistic competition involves many firms selling differentiated products while oligopoly is characterized by a few firms dominating the market. Both structures mix elements of monopoly and pure competition.
Step-by-step explanation:
Monopolistic competition and oligopoly combine, in differing degrees, characteristics of pure competition and pure monopoly. Monopolistic competition is a market structure where many firms sell differentiated products, which means that while the products serve a similar purpose, they have unique characteristics that set them apart from one another. This differentiation can come from physical attributes of the good or service, the location from which it's sold, intangible aspects or brand perceptions. On the other hand, oligopoly is a market structure dominated by a small number of firms. Examples include the commercial aircraft industry, dominated by Boeing and Airbus, and the U.S. soft drink industry with Coca-Cola and Pepsi at the forefront. Barriers to entry are high in oligopolistic markets, enabling firms to exercise significant control over the market, engaging in strategic decision-making including pricing and output, which is influenced by the actions of competitors. These market structures represent a blend of monopoly power and competitive behavior, unique from both pure competition and pure monopoly.