Symantec Endpoint Encryption contains Drive Encryption, and Removable Media Encryption. The management server is hosted on an existing Windows server in your environment, using Microsoft SQL Database for storage and an IIS web site for communication between client and server.
Symantec Encryption Management Server is a standalone soft appliance. It is a customized version of CentOS, and can handle encryption of email as well as deploying clients for drive encryption, FileShare (encrypted files/folders), client-side email encryption, and encrypted Zip and Virtual Disks. It has a self-contained PostgreSQL database, and runs the management console and Web Email Protection services using a self-contained Apache web server.
Note that as an additional difference, the new versions of Symantec Endpoint Encryption do not have the ability to be utilized as a standalone, single client installation, while the Symantec Encryption Desktop client does.