VoIP stands for voice over internet protocol, and SIP stands for session initiative protocol. The chief difference between SIP and VoIP is their reach. VoIP is a group of technologies that are concerned with setting up phone calls across packet networks like the internet.
SIP falls under the umbrella of VoIP technologies. SIP is a protocol that regulates, initiates, dismisses, and redirects calls. It employs a special language which is utilized by the phones as a form of communication.
Originating VoIP telephone calls entail signaling, channel set up, and encoding. SIP is not disturbed with how the voices carry across the network; however, it is responsible for initiating and maintaining real-time sessions, which include all different media.