In a Zero Trust model, adaptive identity and policy-driven access control are crucial components. The model requires verification of who is requesting access and determines what level of access is appropriate based on policy. This enforces granular access controls by ensuring no implicit trust is given and access is provided strictly on a need-to-know basis, aligning with the principles of least privilege access. Unlike firewall rules which traditionally focus on the perimeter, and device compliance which does not necessarily determine access to specific resources, adaptive identity and policy-driven access control define and enforce who can access certain resources under specific conditions.