Web cameras (webcams) are specially designed for transmitting live video or images while online.
Normal video cameras (like your digital camera) are used to record film footage. You do not need to connect them to the computer, so they can be used anywhere as long as the batteries are charged. The recorded video is stored on a tape or the hard disk of the device.
By contrast, webcams are used in conjunction with computers, and require network access via the computer's Internet connection. Software that supports online video transmission allows the device to be used in video chats with other users.