The cost difference can be large for a high-volume user. However, the cost differential can be deceiving. VANs and other traditional EDI service providers give their subscribers more than just data transmission. For example, VANs typically act as a trusted third party, providing an audit trail of transmissions, so if a company doesn't get a response to a document, it can check through the VAN to find out what happened. If a company decides to use an ISP, they have to add in all the things that they would have to pay somebody else to do internally.
Speed is another matter.
The Internet has the potential to be quicker. The data rate on the Internet is also faster. If a business could simply call up another company's Web page, fill out a form in the browser and return it securely, that would reduce costs substantially and make EDI an option for a multitude of small businesses that can't afford it now. Another advantage to the user of Internet-based EDI is the Internet's momentum in electronic commerce. The Internet offers the potential to open up a panoply of electronic trading partners that includes virtually all companies with an Internet address, not just those who have agreed to do business using specific applications over a proprietary network.