VMware makes available two bare-metal hypervisors; ESX and ESXi, which form the foundation of their virtualization product line. both hypervisors do the same thing when it comes to virtualization, they only differ in packaging. ESX is shipped with a Linux derived operating system called service console, and a VMware kernel called VMkernel. the service console include features found on operating systems like firewall, Networking features, and web browser – basically, the service console is a streamed line Linux operating system that let you execute and run many operating system like commands. VMkernel is the foundation of ESX and ESXi virtualization, and it is in charge of allocating and scheduling resources for guest virtual machines. in other words, VMkernel is the real “operating system” of ESX and ESXi.
As you probably figured, the hypervisor does not need the service console to run, so that’s what they did with ESXi, they removed the service console from the hypervisor. the good thing is that by doing that the hypervisor is now very small, and the bad thing is that by stripping off the service console ESXi has less support for hardware, and updating drivers on ESXi requires a VMkernel update also.
So, which is better, ESX or ESXi?
you can do the same thing on both hypervisor, they both support the same virtualization features, so it becomes a matter of preference. I personally like ESX for the custom options it offers, and size partitioning. though I trust VMware with the ESXi speed-light installation without any decision on my side, I rather customize the installation myself.
so to summarize everything, the difference between ESX and ESXi is the service console. remember ESX has a service console, ESXi does not.
