The difference between VoIP and HTTP (Hypertext Transfer Protocol) is that VoIP is a broad technology category that includes any voice communications over the Internet. It facilitates the transfer of audio signals, such as phone calls, over the internet by packaging audio into data packets. Conversely, HTTP serves as a vital protocol for the World Wide Web. It plays a significant role in facilitating the transfer of hypertext documents, like web pages, from web servers to client browsers.