Marketing management can refer to one of two concepts.
The first meaning is the management of the activities traditionally viewed as being in the domain of marketing function within an organisation. These activities or functional areas usually include selling and promotion (advertising and public relations). In some cases distribution is also included.
The second meaning is the more modern usage of the term. In this sense, marketing is viewed not as a functional area of a firm, but rather as a business philosophy. The fundamental tenet of this philosophy is the centrality of the customer. Simply put, businesses exist to serve customers. Customers are the source of revenue, and hence survival, for the business. In this sense marketing means serving the market. It is most definitely not a synonym for selling.