Customer and User

There is a difference between who the customer is and who the user is.  Knowing the difference between the two will help you understand whom to sell to and for whom you need to design and create your products and services.  Not knowing the difference between the two could lead to losing sales.  It could also lead to a poor customer experience.
Rather make sure that you and your team are clear on the difference between the two.  If you are unsure then it is wise to ask these questions during the customer interview.