1. REST has no WSDL interface definition
2. REST is over HTTP, but SOAP can be over any transport protocols such HTTP, FTP, STMP, JMS etc.
3. SOAP is using soap envelope, but REST is just XML.
UDDI is a directory service where companies can register and search for Web services.
WSDL is an XML-based language for locating and describing Web services.
SOAP is an XML-based protocol to let applications exchange information over HTTP.
Or more simple: SOAP is a protocol for accessing a Web Service.
Web Services can convert your application into a Web-application, which can publish its function or message to the rest of the world.
The basic Web Services platform is XML + HTTP.
XML provides a language which can be used between different platforms and programming languages and still express complex messages and functions.
The HTTP protocol is the most used Internet protocol.
Web services platform elements: