I think there's a linkage here, and maybe it's best to explain it in the context of the system.
A bank always starts from culture. You want to have a strong culture because that articulates what you are trying to build as an organization: how you want your employees to behave, how you want the client relationship to look, and how you want the client to feel. You build that then into the code of conduct, which should articulate what that relationship should look like and what sort of values you want to embody within the organization. That gets translated into the actions and the directions for the employees. It all flows through, and then you monitor performance against that.