Question: SSO and ECP profiles sharing the same URL.

If I have a SAML 2.0 protected resource located at 
a particular URL, how does a Service Provider know that the requestor of the 
resource is using the Web SSO Binding or the ECP Binding?  Must they be at separate URLs or is there some mechanism (HTTP 
header values?) such that an ECP can let the Service Provider know 
that it is more than a browser?

 

Thanks,

 

--Dave