What is difference between REST and WebService (SOAP), I looked at the facebook api, they use HTTP headers and some parameters (probably xml or non) and return result in xml, where else SOAP does exactly same, HTTP headers + xml parameters and returns headers + xml.

REST also requires some authenticated token where else SOAP uses http session which is exactly same token used for auth and other information. All I can see that SOAP is little advanced version of REST? 

Or are there any other performance considerations? Reading about REST just talks very high level of client server communication but even SOAP does exactly same. Can anyone point me where it can define correct boundry of REST and SOAP.

We use lot of SOAP transparently in .net, however I just want to know is it really worth paying attension to REST where currently everything is running outstandingly smooth.

I know REST is an architecture and SOAP is a protocol but my question is in detail that is currently the ASP.NET WebService implementation of SOAP has REST architecture?