A prospect is someone who has NOT bought anything from you yet (you can think of your prospect as a “future customer”). A customer (or client, or buyer) is someone who HAS bought something from you. In your business you will have both types of lists. The important thing to remember is that a list of customers (or buyers) is a lot more valuable than a list of prospects. In my personal experience, a person on your buyer list is worth 10 to 15 times what a person on your prospect list is worth.