Are extranets and VPNs the same thing?

Not really. An extranet is basically a glorified website that enables clients or partners to access the corporate intranet for highly specific, often administrative, functions.

For example, an online newspaper's extranet might allow advertisers to change banner ads. On the other hand, a VPN uses a protocol that allows a remote PC full access to a company's network neighborhood, as if it were actually in the home office.

Although extranets take a variety of forms, some of which can resemble a VPN, they do not have the same function. However, using a more sophisticated authentication and segmentation method, a company can build a separate extranet application on its VPN, saving money in the process.