Proxmox VEVMware vSphereWindows Hyper-VCitrix XenServer
Note: This list is not complete and work in progress. Facts could change from release to release. It provides a very rough overview about some differences and major features.     
Guest operating system support
Windows and Linux (KVM)
Other operating systems are known to work and are community supported
(OpenVZ supports Linux only)
Windows, Linux, UNIXModern Windows OS,
Linux support is limited
Most Windows OS, Linux support is limited
Open Sourceyesnonoyes
OpenVZ container (known as OS Virtualization)yesnonono
Single-view for Mangagement (centralized control)yes
Yes, but requires dedicated management server (or VM)
Yes, but requires dedicated
management server (or VM)
Simple Subscription StructureYes, one subscription pricing,
all features enabled
High AvailabilityyesyesRequires Microsoft Failover clustering, limited guest OS supportyes
Live VM snapshots: Backup a running VMyesyeslimitedyes
Bare metal hypervisoryesyesyesyes
Virtual machine live migrationyesyesyesyes
Max. RAM and CPU per Host160 CPU/2 TB Ram160 CPU/2 TB Ram64 CPU/1 TB Ram?
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