Closing is identifying the pain point and potential to help mitigate/relieve a problem or provide a need or fill a gap for the client. Sales is selling a product for the sake of selling or bottom line, think of quotas, for example. The goal is not to identify the best partnerships and outcomes, but to sell a certain amount of units with that being the optimum objective. Closing is opting for win-win and solving a problem for them that is authentic.