Monopolies and competitive markets are two extreme types of market structures. However, they have the following similarities.Cost functions are the same.Both aim to maximize profit and minimize cost.The decision to shut down a firm in any of these markets is the same.The noticeable differences between a competitive and monopoly market are as follows.The number of competitors in a competitive market is more than that in a monopoly market.The demand slope in Monopoly is downward sloping, whereas, in a competitive market, the demand curve is flat. In a competitive market, a firm can sell as much as it wants at the market price. Irrespective of the market curve, in a competitive market with thousands of firms, the residual demand curve of an individual seller is mostly flat. At the same time, a monopolist would have to accept a lower price if it desires to sell a significantly high number of products.