Simply users use and customers buy. Grow your user base and your customer base will also grow.
All aspects of a product influence users. Customers pay for their service or product.
Users are the people who interact with the company through digital media and technology. A company would have more users than customers.
You must meet the expectations of the user and make things simple and usable to maximize user satisfaction. Customers may be affected by pricing and availability which are separate from UX.