VM-Host affinity: This is useful when you want that your VM should run on a particular ESXI host only.

For Example: running and oracle DB server which has socket BASED license. If your environment is having heterogeneous hosts than migrating such VM to a host which has different CPU configuration can violates your license and can cause trouble.

VM-Host anti affinity: This is useful when you want that a particular VM should not run on some particular Esxi hosts.

For Example: your environment has heterogeneous hosts and all the hosts don’t have Numa ARCHITECTURE and you want to get benefits of the vNuma inside your VM. In this CASE you would want your VM to run only on those servers which SUPPORTS Numa.

VM-Host affinity: This is useful when you want that your VM should run on a particular Esxi host only.

For Example: running and oracle DB server which has socket based license. If your environment is having heterogeneous hosts than migrating such VM to a host which has different CPU configuration can violates your license and can cause trouble.

VM-Host anti affinity: This is useful when you want that a particular VM should not run on some particular Esxi hosts.

For Example: your environment has heterogeneous hosts and all the hosts don’t have Numa architecture and you want to get benefits of the vNuma inside your VM. In this case you would want your VM to run only on those servers which supports Numa.