VMWare Workstation (and the former Microsoft Virtual PC) provide simple virtualisation. They allow you to run a few virtual machines on your local computer, and build a few virtual networks to simulate production networks.
Hyper-V and VMWare ESXi are for running production networks. They are "Class 1" hypervisors, where the Hypervisor is the entire OS. The underlying OS does nothing except provide virtualisation. Typically they:
- Have massive amounts of RAM
- Have shared, clustered storage
- Permit the movement of a virtual machine between physical hosts seamlessly, without powering down the guest
- Permit failing over of an entire network to a 2nd remote datacenter, kept in sync by block-level replication of the SAN
- Allow the building of redundant, fault tolerant services
As a really isolated example, when you restart your computer running VMWare Workstation, to get your guests back online you need to:
- Wait for the server to boot
- Log in
- Start VMWare Workstation
- Click "Play" on all your vm's.
On Hyper-V or ESXi, the procedure is:
- Do nothing
Because your virtual machines were all migrated to other hosts before the restart, or even if you don't have other hosts then they will be booted according to the rules you entered.