VMware ESX/ESXi/Hypervisor comparisons

Main Difference between ESX and ESXi

VMware ESXi is VMware’s most advanced hypervisor architecture. Learn about the differences with the previous generation architecture, VMware ESX

Capability	ESX 4.1	ESXi 4.1	ESXi 5.0
Service Console	Present	Removed	Removed
Admin/config CLIs	COS + vCLI	PowerCLI + vCLI	PowerCLI + vCLI (enhanced)
Advanced Troubleshooting	COS	Tech Support Mode	ESXi Shell
Scripted Installation	Supported	Supported	Supported
Boot from SAN	Supported	Supported	Supported
SNMP	Supported	Supported (limited)	Supported
Active Directory	Integrated	Integrated	Integrated
HW Monitoring	3rd party agents in COS	CIM providers	CIM providers
Serial Port Connectivity	Supported	Not Supported	Supported
Jumbo Frames	Supported	Supported	Supported
Rapid deployment and central management of hosts via Auto Deploy	Not Supported	Not Supported	Supported
Custom image creation and management	Not Supported	Not Supported	Supported
Secure syslog	Not Supported	Not Supported	Supported
Management interface firewall	Supported	Not Supported	Supported

See the KB article for a detailed comparison. There is one more KB for such comparison.

Compare ESXi to Other Vendors' Offerings

Hypervisor Attributes	VMware ESXi 5.0	Windows Server 2008 R2 SP1 with Hyper-V	Citrix XenServer 5.6 FP1
Small Disk Footprint	144 MB disk footprint (VMware ESXi)	>3GB with Server Core installation ~10GB with full Windows Server installation	1GB
OS Independence	No reliance on general purpose operating system (VMware ESXi)	Relies on Windows 2008 in Parent Partition	Relies on Linux in Dom0 management Partition
Hardened Drivers	Optimized with hardware vendors	Generic Windows drivers	Generic Linux Drivers
Advanced Memory Management	Ability to reclaim unused memory, de-duplicate memory pages, compress memory pages	Only uses ballooning. No ability to de-duplicate or compress pages.	Only uses ballooning. No ability to de-duplicate or compress pages. Does not adjust memory allocation based on VM usage.
Advanced Storage Management	VMware vStorage VMFS, Storage vMotion, Storage DRS	Lacks an integrated cluster file system, no live storage migration	Lacks an integrated cluster file system, no live storage migration, storage features support very few arrays
High I/O Scalability	Direct driver model	I/O bottleneck in parent OS	I/O bottleneck in Dom0 management OS
Host Resource Management	Network traffic shaping, per-VM resource shares, set quality of service priorities for storage and network I/O	Lacks similar capabilities	Lacks similar capabilities
Performance Enhancements	AMD RVI, Intel EPT large memory pages, universal 32-way vSMP, VMI paravirtualization, VMDirectPath I/O, PV guest SCSI driver	Large memory pages,  4-way vSMP on Windows  2008 and Windows 7 VMs only	No large memory pages, no paravirt guest SCSI device, Requires inflexible SR-IOV
Virtual Security Technology	VMware VMsafe™ Enables hypervisor level security introspection	Nothing comparable	Nothing comparable
Flexible Resource Allocation	Hot add VM vCPUs and memory, VMFS volume grow, hot extend virtual disks, hot add virtual disks	Only hot add virtual disks	Nothing comparable
Custom image creation and management	VMware Image Builder allows administrators to create custom ESXi images for different types of deployment, such as ISO-based installation, PXE-based installation, and Auto Deploy.	Nothing comparable	Nothing comparable
Auto Deploy	vSphere Auto Deploy enables faster provisioning of multiple hosts. New hosts are automatically provisioned based on rules defined by user.	Requires in-depth setup in Systems Center Configuration Manager	Nothing comparable
Management Interface Firewall	ESXi Firewall is a service-oriented and stateless firewall that protects the ESXi 5.0 management interface. Configured using the vSphere Client or at the command line with esxcli interfaces.	Nothing comparable	Nothing comparable
Enhanced Virtual Hardware	32-way virtual SMP, 1TB virtual machine RAM, Non hardware accelerated 3D graphics, USB 3.0 device support, Unified Extended Firmware Interface (UEFI).	4-way virtual SMP only, 64 GB RAM per virtual machine	8-way virtual SMP only, 32 GB RAM per virtual machine