VMware compare is similar to the LDAP compare. In this case it uses the VMware REST API and tries to connect to your vSphere system. It further will read out all the guest VM’s and some basic data, store it in a table and try to combine it with the servers in the IT Assets database. This expects that the guest VMs named after their actual host-name what is a common practice.
This allows you to find undocumented guest VMs as well as e.g. marked as retired systems or simply compare CPU, RAM information from VMware against what is documented in the IT Assets database.
In the end, it is a mini audit of your VMware environment.