The main uses of a VPN service are to provide ANONYMITY by hiding your IP address and to mantain PRIVACY by sending encrypted data across the Internet. There are various types of VPN connections available but in general many VPN providers offer PPTP and OpenVPN connections due to their simplicity and efficiency. They both provide different levels of encryption, in addition to anonimity.
The Point-to-Point Tunneling Protocol (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.
OpenVPN is a free and open source software application that implements virtual private network (VPN) solutions for creating secure point-to-point or site-to-site connections in routed or bridged configurations and remote access facilities. It uses SSL/TLS security for encryption and is capable of traversing network address translators (NATs) and firewalls.
PPTP vs OpenVPN ?
One of the biggest issues that drives our choice between PPTP and OpenVPN, and an issue that we have no control over, is that sometimes ISP block PPTP connections. There is nothing to be done about this, and in this case using OpenVPN is your only alternative. PPTP has some unique advantages, but a change to OpenVPN may be a good thing.
PPTP works with almost all the Operating software and not requires any software to use. It also works with many mobile devices such as Iphone, Ipad, Windows mobile and can easily be setup on them. In contrast, OpenVPN setup can be a little more complicated compare to PPTP, but with the right directions you should be able to setup the connection without much difficulty. Note that OpenVPN does not work with mobile devices.
PPTP encryption method uses the password as the key and it’s datastream carries a retrievable hash password. If someone in middle intercepts your traffic and cracks the encryption (which is not easy though possible) then he can decrypt your traffic. Where as OpenVPN uses a very strong encryption (blowfish) method. Even if someone does intercept your traffic, they can do nothing with it. This makes OpenVPN more secure than PPTP. To read further about OpenVPN security encryption keys follow this link.
Which to use ?
If you're looking to get high security and are more concerned about the secure transfer of data, then you should use OpenVPN. If you're looking for easy setup OR VPN usage on mobile devices then PPTP is the one for you. There are other protocols available such as L2TP or IpSec, but they are not as user-friendly or cost-efficient.