Due care and due diligence are security concepts that are closely related. Due care is using reasonable care to protect the interests of an organization. An example of due care is having management create a formalized security structure for the organization that contains various documentation such as baselines, guidelines, and security policies.
On the other hand, due diligence is practicing the activities set forward from the due care process. This means personnel are expected to follow security policies, baselines, or guidelines among other documents.