I think the difference lie in the class. As a native Chinese, we use "顾客” like "customer" in English, it is more like a low-end consumer in a 2C business. And "客户“ is more high-end people, like "client" in English, it is often used in 2B case. For example, the people come to your restaurant is your "顾客”, but the people come to a consulting firm for business is the "客户“ for the firm.

Thanks all dears:)

A bit more on English meaning of "customer" and "client". When money is exchanged directly, then it is the customer. When a service is rendered and payment at a later date, then it is a client. Hence when you go to a shop to buy something, then you are a customer. If you go to see a lawyer, then you are a client since the attorney won't charge you until a contract is signed and payment is then required.

Yes. 顾客 is more like "customer" while 客户 is more like "client" in English.

顾客更多是等来的，客户更多是找来的。The customer refers to the people who come to you of their own initiative , whereas the clients might be invited or found from marketing.