Can you guess what the difference between a URL and URI is? Yeah I know that URL is a URI but not otherwise. Basically a Uniform Resource Identifier is a Resource e.g. a domain name and will return a response depending upon your device (WML/HTML) but URL is a representation that is if a GIF file is used that will be returned as GIF only and will not be converted. Read more here @ URI vs. URL: What’s the Difference?