C2S : Client To Side VPN
A single user (e.g. a remote employee) connects securely to the company network via VPN client software.
S2S : Side to Side VPN
Permanently connects two whoe networks in different locations (e.g. HQ and a branch office) over the internet.
SSL VPN : Browsed-based (Clientless)
Access via a web browser over HTTPS/SSL - no VPN client to install. Fast for temporary / guest access.
