Gold plating usually refers to the addition of features that were not in scope, and which do not add enough value to justify the time spent in producing them.
Customer delight is all about meeting the customer's needs.
Gold plating implies a lack of communication and/or understanding of the customer's requirements. Customer delight is exactly the opposite; by understanding what the customer needs, even if they haven't made it explicit, you can product features that are useful, functional, and impressive to the customer.
Put it this way - gold plating is investing time and resources in features that are often not needed or wanted, delighting the customer is investing time and resources in features that are needed and wanted. Saving Changes...
