OpenStack OR CloudStack

[hossein zabolzadeh]

Hi,
I hear a lot about openStack, and its rapid development and improvement. I
also know that we have two type of cloud paradigm. Amazon and Vcloud. And
also know that cloudstack is vcloud like CMP. But What really these words
mean?
Can you take an example(Technical Example) to show the real differences
between AWS and Vcloud cloud approach?
>From a technical point of view, what is a real difference between these tow
types of cloud approaches?