Hello,
The downloads are Compressed Files.
I would recommend you to check these Articles:
Symantec Endpoint Protection clients download full definitions from Group Update Provider or from Symantec Endpoint Protection Manager
http://www.symantec.com/docs/TECH122612
Symantec Endpoint Protection Manager Auto-Upgrade using RU6/RU6a Manager pushes full client instead of delta
http://www.symantec.com/docs/TECH137774
With default LiveUpdate content revision settings configured within the Symantec Endpoint Protection Manager, clients are downloading full definition updates instead of delta updates
http://www.symantec.com/docs/TECH94916
Hope that helps!!