does Nutanix software sit as an application on top of the Operating System?
Yes indeed. Nutanix is not a fully functioning operating system that would run an Apple or Dell computer on its own. Unfortunately I cannot answer your second question as I am not familiar with what Microsoft truly offers in this area.
Thank you to everyone who responded kindly to my original post. I greatly enjoyed reading the Nutanix bible, and trying to make sense of what the company truly did.
Brandon