In an ACI policy model, the separation of logical and concrete domains allows for the definition of policies in a logical space without specifying physical details. These policies can then be applied flexibly to the concrete entities, providing a clear abstraction layer for network configuration. References: Cisco ACI policy model documentation.
[Reference: https://www.cisco.com/c/en/us/td/docs/switches/datacenter/aci/apic/sw/1-x/aci-fundamentals/b_ACI-Fundamentals/b_ACI-Fundamentals_chapter_010001.html#:~:text=Policy%20Model%20Key%20Characteristics,-Key%20characteristics%20of&text=As%20a%20model%2Ddriven%20architecture,devices%20attached%20to%20the%20network.]