Well in a practical sense there is no difference but there is a difference.Nick said:The expressions are identical -- there is no difference in meaning. Both are equally common, I think.
Tim Burness Lee said:The Internet ('Net) is a network of networks. Basically it is made from computers and cables. What Vint Cerf and Bob Kahn did was to figure out how this could be used to send around little "packets" of information. As Vint points out, a packet is a bit like a postcard with a simple address on it. If you put the right address on a packet, and gave it to any computer which is connected as part of the Net, each computer would figure out which cable to send it down next so that it would get to its destination. That's what the Internet does. It delivers packets - anywhere in the world, normally well under a second.
Lots of different sort of programs use the Internet: electronic mail, for example, was around long before the global hypertext system I invented and called the World Wide Web ('Web). Now, videoconferencing and streamed audio channels are among other things which, like the Web, encode information in different ways and use different languages between computers ("protocols") to do provide a service.
The Web is an abstract (imaginary) space of information. On the Net, you find computers -- on the Web, you find document, sounds, videos,.... information. On the Net, the connections are cables between computers; on the Web, connections are hypertext links. The Web exists because of programs which communicate between computers on the Net. The Web could not be without the Net. The Web made the net useful because people are really interested in information (not to mention knowledge and wisdom!) and don't really want to have know about computers and cables.