Difference between ESX vs ESXi

Wondershare Recoverit Authors

Sep 14, 2021 • Filed to: Windows Computer Solutions • Proven solutions


Considering that VMware accounts for 75% of the global server virtualization market, it won't be false to call it the undisputed leader in server virtualization. VMware allows for virtualization in the most cost-effective way even when the virtualization is highly resource-intensive. No matter what level of VMware software you are using, ESX vs. ESXi is always a hotly debated topic.

In this article, you'll learn about the difference between ESX and ESXi so you can make an informed decision.


Whether you are just starting out with VMware or have been using it for a long time, you are bound to come across these terminologies sooner or later.

Making the right choice between ESX vs ESXi is critical when considering going virtual. Much of your success will depend on how well you choose and install the correct version of VMware software in your data center. Simply put, the two versions differ in many ways including performance, memory usage, and storage space.

1) Performance: By default, VMware uses Service Console (ESXi) instead of an entire operating system (ESX). This means that the core management functions like hardware abstraction layer (HAL), virtual machine monitor (VMM), and virtual device interface (These are two types of VMware hypervisor architecture, designed for “bare-metal” installation, which is directly on top of the physical server (without running an operating system). The aim of our article is to explain the difference between them.

2) Memory usage: ESXi uses less amount of physical memory than ESX.

3) Storage Space: ESXi can take advantage of VMFS-5 volumes (with space larger than 2 TB) while ESX cannot.

4) Installation: A server running ESXi doesn’t require a CD/DVD, but an installation disc is necessary for the initial setup. Once that process is done, you just need to upload the image to perform updates or install new versions. To upgrade ESX, it's first necessary to boot from the CD/DVD and then upload the new image before rebooting into it. Also, in case of vSphere Client installed on Windows OS with an internet connection you don't need any ISO files for installing or updating VMware

ESX vs ESXi: Key Differences

Generally speaking, both are similar as far as the functionalities are concerned. What differentiates them is their architecture and management of operations. To help you understand or decide which one to use for better security, reliability, and management, then ESXi should be your choice because it has a clear edge in these departments. Also, ESXi isn't reliant upon any OS. If we talk about VMware's own recommendations, then you need to migrate from ESX to ESXi because that’s what they recommend to the users. It’s a great way to gain maximum benefits from their hypervisor.

Console OS in ESX

The architecture of ESX is designed to get help from COS for a certain task. On the other hand, ESXi doesn’t have to rely on a Linux-based Console Operating System (COS). This is a key difference between both.

The use of COS in ESX is not extensive though. The only function of COS in ESX is to boot the server, followed by loading the vSphere hypervisor in memory. This is the only function of COS on which ESX relies upon. Other than that, its role is very limited.

Console Operating System demands time and effort to keep it secure and maintained, which is not a desirable feature to have. Because of its demanding nature and other flaws, it has the following limitations:

There are quite a few benefits of preventing hypervisor from not relying on COS. When initially introduced in the 3.5 VMware release, ESXi no longer needed to rely on COS. It loads into the memory directly from the boot. This has resulted in many benefits. The few of them are as follows:

The above discussion presents a good idea of the key difference between ESX and ESXi. The only major difference between both has resulted in solving a number of challenges related to security, performance, and reliability.

ESX vs. ESXi: Basic Features of ESXi

Here are some of the key features of ESXi at a glance:

Smaller footprint

When compared to ESX, the footprint of ESXi is smaller. The footprint is the space or memory a software occupies on a disk. When we look at the ESXi 6.7, it occupies 130 MB while the ESXi ISO image of the 6.7 version occupies 325 MB. This means that the ESXi’s footprint is not huge by any means and it doesn’t causes any disk space issues.

Enhanced security

After the 6.5 release, the array of security features has become even more comprehensive. You have access to a wide variety of security tools and features that help to protect ESXi hosts. You can prevent unauthorized access and misuse of your system. With the inclusion of the encryption features, you are allowed to encrypt your Virtual Machines. You can also encrypt files, virtual disk files, and more. Another highly useful feature is its role-based access control. It lets you define how extensive access you want to give to certain users in infrastructure. It can limit unauthorized access and misuse to a great degree.

Finally, audit logging is another vital feature. It allows for effective monitoring of the infrastructure.

Rich ecosystem

VMware's ecosystem is very well-supported. For example, you can combine third-party apps with VMware to improve your management, which will help you manage a diverse and complex infrastructure. One of the VMware tools named Global Support Services (GSS) is a great solution to identify whether or not a problem you’re facing is a third-party software related problem or hardware related problem. This rich ecosystem of multiple tools and third-party enablement makes it an overall great experience.

User-friendly experience

One of the major improvements is on the user experience side. The 6.5 release came with its vSphere Client having HTML5 version. This in particular is responsible for improving the user experience. Another useful feature is the inclusion of CLI in vSphere, which enables users to give basic commands to the system, given that the machine from which the command is generated has access to the system. It also allows the use of REST APIs for development tasks. This feature optimized the application provisioning, conditional access, and so on.


To conclude our comparison of ESX vs ESXi, we would call both of them quite similar as far as the functionalities and performance are concerned. This statement becomes even more true when we compare the 4.1 release version. The major difference between both lies in the architecture and how they manage their operations. ESXi isn’t reliant upon any OS, making it suitable for solving many security and reliability-related concerns. Migrating to the ESXi architecture requires careful preparation. However, you won’t face downtime during the migration.


ESX became ESXi in 2010. VMware rename ESX to ESXi when it released version 4.1.

Yes. You get an inbuilt firewall in all ESXi hosts. The firewall sits between the management interface and framework.

Technically, ESXi is free to use. You don’t need to pay anything other than applying a free license.

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