Greetings,
SEP is a file system level scan, meaning it has drivers that allow SEP to scan an item before it is accessed. Scan Engine is a scan on demand process, meaning that it sits and waits for information or an item to be passed to it.
Scan Engine can be used to scan items as they are being submitted through a website or can work with Netapp, EMC filers or MS Sharepoint to scan items as they are committed or modified on the file system.
Definitions cannot be managed by a SEPM for the Scan Engine product. Scan Engine would need to be allowed to pull definitions from the internet or from an LUA server.
The product is managed through a web interface and is very simple in comparison with most Symantec AV scanning products.