This depends upon what product or service they are promoting. Sales is basically that, selling. But marketing is not always research. marketing can be research, but it can also be promoting a specific brand or product. Promoting can be anything from deciding what your logo will look like to deciding who your target audience is to deciding what price your will ask for the product or service you are pushing. All of these items and many more can all fall under the umbrella of marketing. So the point I am trying to make is that a sales and marketing company can be many different things to different people. Here is another example. It can also be deciding on what your advertising campaign will look like. Yes, marketing can have sub specialities like the ones I named above.