Simply put, guidelines are general recommendations; they're not mandatory or required. Employees who don't follow guidelines usually don't have anything happen to them, discipline-wise. Policies are formalized requirements that apply to a specific area or task.

As nouns the difference between policy and guidance is that policy is (obsolete) the art of governance; political science or policy can be a contract of insurance while guidance is the act or process of guiding. As a verb policy is to regulate by laws; to reduce to order.