The Enterprise version contains some proprietary software licensed from 3rd parties that we cannot release under the GPL. Additionally, the automated update system is part of the paid support package not needed with the Community release.
The main difference in the Enterprise version is the use of the Ntru encryption libraries for use in the wireless/smart phone clients. We believe that the private/public key pairs need to be generated on the device. The key gen times for open source RSA and ECC algorithms were unbearable. RSA key gen on a J2ME phone was estimated to be 14 days and ECC was 14 hours! For Ntru, the key gen time is closer to 4 seconds.
The Enterprise server also includes a built-in radius server which we licensed. The main attraction was that it is written in java.
Finally, the Enterprise version is an ISO/Virtual Appliance that requires no knowledge of Linux and is offers a very simple installation procedure. If you're interested in testing the Enterprise, we offer a 30 day evaluation license. You can quickly test the ISO software appliance on your virtual server platform of choice.