HVM & PV instances

Hey folks!! What are these new HVM instances? And how are they different from the PV ones?

Amazon offers HVM and PV operating system options for most instance types.

Para-Virtualization (PV) is means of virtualization support for best performance and stability.
Host and guest kernels should be attached.
1.The stability/Performance is close to the real servers and hardware virtualization.
2.Supports Linux only.

The “newer” option for virtualization is hardware-assisted virtual machine (HVM) whereby the host and guest kernels don’t need to be attached.
It provides complete hardware isolation.
1.Resembles close to a physical server.
2.Can run Linux and Windows.