What is a difference between "Logical CPUs" and "Logical CPUs per host"?

Hello everyone!

In VMware official document "vsphere-51-configuration-maximums" or "vsphere-55-configuration-maximums.pdf" in section "ESXi host maximums \ Compute Maximums" exists to items:

"Host CPU maximums \ Logical CPU per host" ( vSphere 5.1: 160;   vSphere 5.5: 320 )

and

"Virtual machine maximums \ Virtual CPUs per host" (vSphere 5.1: 2048;    vSphere 5.5: 4096)

Question: what is the difference between these two items?

And one more complex thing from maximums:

Virtual machines per host: 512

Hosts per cluster: 32

Therefore, in the cluster can exist Virtual Machines (in maximum): 521 * 32 = 16384

But in document we have only 4000 VMs in maximum.

Why?

Thank you