For items that are selling the salesperson is responsible for consulting advice to customers about products and services in order to receive adequate and accurate information that will lead to a buying decision.
In order to sell Sales is responsible for the introduction. Advising customers about products and services. In order to get the correct information and sufficient to lead to a decision to purchase.
For a product to sell. The salesman for advice. Counsel clients about the products and services. In order to get the correct information and sufficient to the purchasing decision.