Differentiated products: Another feature of the monopolistic competition is the product differentiation. Product differentiation refers to a situation when the buyers of the product differentiate the product with other. Basically, the products of different firms are not altogether different; they are slightly different from others. Although each firm producing differentiated product has the monopoly of its own product, yet he has to face the competition. This product differentiation may be real or imaginary. Real differences are like design, material used, skill, etc. whereas imaginary differences are through advertising, trade mark and so on.