The following are the different types of VPNs :

PPTP ( Point to Point Tunnel protocol ) VPN : Most commonly used VPN. PPTP is a method for implementing virtual private networks. PPTP uses a control channel over TCP and a GRE tunnel operating to encapsulate PPP packets.

Site-to-Site VPN : Site-to-site VPN is a type of VPN connection that is created between two separate locations. Site-to-site VPN can be intranet based or extranet based. 

Intranet-based site-to-site VPN is created between an organization's propriety networks, while extranet-based site-to-site VPN is used for connecting with external partner networks or an intranet.

L2TP ( Layer Two Tunneling Protoco) VPN : L2TP is an extension of the Point-to-Point Tunneling Protocol (PPTP) used by an Internet service provider (ISP) to enable the operation of a virtual private network over the Internet.

IPsec (Internet Protocol Security) : IPsec is a framework for a set of protocols for security at the network or packet processing layer of network communication.

SSL (Secure Sockets Layer) VPN : SSL  is a form of VPN that can be used with a standard Web browser. In contrast to the traditional Internet Protocol Security (IPsec) VPN, an SSL VPN does not require the installation of specialized client software on the end user's computer. 

MPLS (Multiprotocol Label Switching) VPN : MPLS is a protocol for speeding up and shaping network traffic flows. 

Hybrid VPN : A hybrid VPN combines Multiprotocol Label Switching (MPLS) and Internet protocol security (IPsec)-based VPNs.