I recently posted a question about Azure... [is it really an OS?](https://stackoverflow.com/questions/315879/is-azure-an-operating-system-or-a-framework) I understand the technical details, and I got a lot of fuzzy answers... I really want to know... what do you think is the difference between an OS and a Framework?

Just for reference, Azure will be built on top of Hyper-V servers and the virtual machines will be running vanilla Windows Server 2008. It will run services that creates a cloud on top of the many virtual machines which is called Azure. Windows is calling Azure an OS. 

I am trying to understand how to define the difference between an OS and a framework.