Which will give more performance and why? 1) 4 Solaris VM's installed in a Esxi Server or 2)4 Solaris zones created in a Solaris server?

I think Solaris Zones created in Solaris Server as there won't be much overhead involved in zones

The second option, solaris zones created in solaris server will give you more performance.
Overhead caused by Solaris zones is much lesser that the overhead caused by hypervisor.

>> Zones concept is outdated now.
It supports only4 zones maximum >> It is the time of VM's on ESXI hosts.
Can have many number of VMs depending on the host configuration.
Easy to manage the servers and monitor their performance.