Just as in any profession,there are different jobs in marketing that do different things. To get a good grasp of the scope of the different positions and their responsibilities, you could look at the Department of Labor Occupational Outlook Handbook's section on Advertising, Marketing, Promotions, Public Relations, and Sales Managers: http://www.bls.gov/oco/ocoS020.htm
Advertising managers. Advertising managers direct a firm’s or group’s advertising and promotional campaign. They can be found in advertising agencies that put together advertising campaigns for clients, in media firms that sell advertising space or time, and in companies that advertise heavily. They work with sales staff and others to generate ideas for the campaign, oversee a creative staff that develops the advertising, and work with the finance department to prepare a budget and cost estimates for the campaign. Often, these managers serve as liaisons between the firm requiring the advertising and an advertising or promotion agency that actually develops and places the ads. In larger firms with an extensive advertising department, different advertising managers may oversee in-house accounts and creative and media services departments. The account executive manages account services departments in companies and assesses the need for advertising. In advertising agencies, account executives maintain the accounts of clients whereas the creative services department develops the subject matter and presentation of advertising. The creative director oversees the copy chief, art director, and associated staff. The media director oversees planning groups that select the communication medium—for example, radio, television, newspapers, magazines, the Internet, or outdoor signs—that will disseminate the advertising.
Marketing managers. Marketing managers work with advertising and promotion managers to promote the firm's or organization's products and services. With the help of lower level managers, including product development managers and market research managers, marketing managers estimate the demand for products and services offered by the firm and its competitors and identify potential markets for the firm’s products. Marketing managers also develop pricing strategies to help firms maximize profits and market share while ensuring that the firms' customers are satisfied. In collaboration with sales, product development, and other managers, they monitor trends that indicate the need for new products and services and they oversee product development.
Promotions managers. Promotions managers direct promotions programs that combine advertising with purchasing incentives to increase sales. Often, the programs are executed through the use of direct mail, inserts in newspapers, Internet advertisements, in-store displays, product endorsements, or other special events. Purchasing incentives may include discounts, samples, gifts, rebates, coupons, sweepstakes, and contests.
Public relations managers. Public relations managers plan and direct public relations programs designed to create and maintain a favorable public image for the employer or client. For example, they might write press releases or sponsor corporate events to help maintain and improve the image and identity of the company or client. They also help to clarify the organization’s point of view to their main constituency. They observe social, economic, and political trends that might ultimately affect the firm, and they make recommendations to enhance the firm's image on the basis of those trends. Public relations managers often specialize in a specific area, such as crisis management, or in a specific industry, such as healthcare.
Sales managers. Sales managers direct the distribution of the product or service to the customer. They assign sales territories, set sales goals, and establish training programs for the organization’s sales representatives. (See the Handbook statement on sales representatives, wholesale and manufacturing). Sales managers advise the sales representatives on ways to improve their sales performance. In large multiproduct firms, they oversee regional and local sales managers and their staffs. Sales managers maintain contact with dealers and distributors, and analyze sales statistics gathered by their staffs to determine sales potential and inventory requirements and to monitor customers' preferences. Such information is vital in the development of products and the maximization of profits.
See also:
Advertising sales agents: http://www.bls.gov/oco/ocos297.htm
Market and Survey Researchers: http://www.bls.gov/oco/ocos013.htm
Public Relation Specialists: http://www.bls.gov/oco/ocos086.htm
Artists and Related Workers: http://www.bls.gov/oco/ocos092.htm
Authors, Writers, and Editors: http://www.bls.gov/oco/ocos320.htm