SOAP and REST are not interchangeable

Recently I saw this question posted in a forum: “Does REST have better performance than SOAP”?
This question is symptomatic of a fundamental misunderstanding of REST, I think. SOAP is a particular protocol used to implement RPC functionality. REST, on the other hand, is not a technology or protocol, but an architectural style. Systems that were built with the REST architectural style are fundamentally different from RPC based systems. For REST, we think in resources and data.