They define the type and format of the data exchanged between different systems. REST is an architectural style. Many Of You Use Commercialized Soap For Your Washing Needs But You Probably Don T Know What Goes Into Making The Soap You Use L Natural Soap Soap Soap Making 1 SOAP is a protocol. . Explore more on REST API Vs. SOAP vs REST Differences. REST is an architectural style with implementation while SOAP is a protocol with an official standard. SOAP which stands for Simple Object Access Protocol is a highly strict and secure way to build APIs that encodes data in XML. REST which stands for Representational State Transfer is a simpler and more flexible method for building APIs that can transfer data in a variety of formats including XML as well as plain. Difference Between SOAP and REST API.