The power off option for a virtual machine is analogous to disconnecting the power cable on a physical machine.
Powering off a virtual machine does not allow critical operations in the virtual machine, such as writing data to disk, to complete before power off. As an alternative to powering off a virtual machine, you can shut down the virtual machine. This allows critical operations to complete and the guest operating system to shut down before the virtual machine powers off.
In certain situations, such as when VMware Tools is not installed or the guest operating system is not responding, shut down might not succeed and using the Power Off option is necessary.