Yes, There is difference between Users and Consumers w.r.t marketing.
Consumers is the new neologism, for the marketers , market is the place where there is exchange of money and product and merchants. This activity ends after the exchange is done and consumer will move to another phase i.e. will use the product and becomes users.
The basic difference is till when the buyers does not use the products he is consumer for the marketers as they will bring them something in exchange.
Marketing focus more on How to sell products to consumers and much concerned with usability.