- The SOAP 1.1 spec is defined in one document. The SOAP 1.2 spec is defined in three documents (a primer, the basic messaging framework, and the adjuncts (RPC convention, SOAP encoding, message exchange patterns, etc.))
- SOAP 1.2 is defined in terms of the XML Infoset.
- The namespaces are different.
- SOAP 1.1 has a number of ambiguities. SOAP 1.2 is much more precise and concrete.
- SOAPAction is required in SOAP 1.1 and optional in SOAP 1.2.
- SOAP faults are different.
- SOAP 1.2 provides support for SOAP versions.
This was first published in July 2002