What is the difference between a SSL VPN and  PPTP VPN?

Secure Socket Layer Protocol (SSL VPN) is a virtual private network that uses secure socket layer protocol or Transport Layer Protocol to provide secure between remote users and internal network resources.
Point – to – point Tunnelling Protocol (PPTP VPN) is one of the oldest and most popular forms of VPN developed by Microsoft. It is the fastest of all CVPN protocols. PPTP VPN is not secure due to its weak encryption. PPTP also have an advantage of a pre-installed client base on windows platforms.
Hope this information is helpful.