Hi,
Easy VPN Server is a feature that allows client-to-site VPNs between hardware devices (Routers, Firewalls, Concentrators). Therefore you have a central site having a Easy VPN Server (routers from 1800 series, ASA Firewalls)to witch all the spokes are connected, and all the spoke Easy VPN clients ( 800 series Routers, ASA Firewalls) can connect in a similar way as the Cisco VPN client software.
There are many benefits for Cisco Easy VPN like: it works even if the spokes are behind ISPs with dynamic IP assignment, admission policies are controlled from the central point, tunnels can be initiated on-demand or always-on.
For more details:
http://www.cisco.com/en/US/products/ps6659/products_ios_protocol_option_home.html
Please rate if this helped.
Regards,
Daniel