This is a simplified and very brief introduction which I hope will answer your question:
SOAP web servcies: When you issue a web service request, you are typically invoking some processing in the web service server that, optionally using some indata, may or may not produce a result that is returned.
RESTful web services: Issuing a request typically retrieves the representation, commonly in XML or JSON, of a resource identified by the URL to which the request was sent.
Issuing a request for an URL in a browser or using a HTTP client program typically retrieves some data from the URL in question. The data can be static, but can also be dynamically generated.