A customer day is actually a specific type of client event. The difference lies in the audience and the goal.
A customer day focuses specifically on existing customers. The goal is usually to show appreciation and strengthen the relationship. Customer retention is the intended effect. The format is often a day with a substantive programme, networking moments and entertainment.
A client event is broader. It can be aimed at customers, but also at partners, suppliers, prospects or a mix of these. The goal can range from relationship maintenance to business development or brand positioning.
The format differs too. A client event can be a private dinner, an exclusive conference, an inspiration session, a festive gala or an informal networking drinks. The choice depends on who you want to reach and what you want to achieve.