In guest memory utilization reported with physical memory and kernel memory in the virtual machine is about the utilization with in the guest resource.
this is help to validate the memory resource need to virtualmachine, like you allocated 2 GB ram and in inguest you see 2GB full utilization and in addition paged, then we need to increase the resources to virtual machine. to trouble shoot the internal guest resource usage and needs. that needs to be compared with physical resource usage when come to performance issue.
To know exact physcial resource utilization, how much physical resource is allocated and how much is swapping out to a vm, you can check the vcenter performance counter, which is updated with a delay time.
Take a putty to esxi, enter esxtop and type m, see the virtual machine memory usage values .
below kb for resource allocated to VM:
http://kb.vmware.com/kb/1033115
refer esxtop usage;