What is the difference between ESXi and vSphere?

I get a lot of confusion from customers about the right terminology for VMware products. I’m not surprised, because VMware frequently re-brand and re-name products and we all get confused.

VMware’s Hypervisor

Here’s the key one. When you download VMware’s Hypervisor from the VMware website, the filename includes VMVisor – this is

not the product name, it’s a byproduct of the software build process used internally in VMware. The VMware Hyper Visor is called ESXi – and this is a rename of the original product called ESX (believe it or not, these initials were originally for “Elastic Sky
X”). The original ESX depended upon a Parent Partition that was a specialised version of Linux based on RedHat – then VMware developed a Type 1 (bare metal) hypervisor and called it ESXi – it’s completely different to ESX, but 100% compatible in terms of features and functionality. The little i refers to “integrated” and was originally a free product – but not any more…
The ESXi Hypervisor is not, and does not have, an operating system, but responds to some Linux-style commands.

What is vSphere, and how is it different to ESXi?

The name “vSphere” has been used by VMware since version 4, to refer to the wider system that includes the Hypervisor (ESXi) and other components, delivered as free appliances, such as; vSphere Replication, vSphere Data Protection, vShield Endpoint and App HA (using vFabric Hyperic) – depending on your licensed edition. So, if you buy vSphere, you get ESXi Hypervisor plus access to free (and optional) components.

So, in summary; VMvisor = ESXi = VMware Hypervisor = vSphere (hypervisor component)

What is the right name for VMware products?

Apple seems to have taken ownership of anything starting with lowercase “i” – and VMware seems to own everything that starts with lowercase “v”. But there are some interesting exceptions;

Uppercase Vs

• VADP – VMware APIs for Data Protection
• VAAI – VMware APIs for Array Integration
• VSAN – VMware Storage Array Network
• VMFS – VMware File System

Misunderstood names

There are some names that are often mis-represented;

• vC Ops – vCenter Operations Manager. It’s often referred to as vCops, but that’s not the official name. Why is not called vCOM? Why is the URL to access it /vcops-vsphere?
• vFRC – vSphere Flash Read Cache. For a while it was referred to as vFlash, but VMware need to have people understand it is a read cache and not used for writes
• vCAC – vCloud Automation Center. It’s not pronounced v-cack, but v-cake

I hope that this has helped you out – let me know in the comments if you have any more