I appreciate the test as always, but this time I must disagree, I'm sorry
SEP was built for company and they has huge reason why this software not released for home users. SEP is not a simple antivirus, not a simple internet security, it's an excellent protection for
Network with many features etc, but...in order to make SEP run properly, users cannot run it under default settings jut like when it installed, its quite different than other Norton's product for home users, if not configured properly, then SEP will simply fail. It will requires a manual book to read and understanding the whole features in SEP and manual configuration. And since you also said and admitted by your self by saying "prefer Norton Internet Security which is more efficient" it is true...then how in the world this Norton's product gave different results? especially since this was built for company? it should provide better result, the answer is : because it's not a simple internet security.
Both N.Nvt and Umbra can provide more details and explanation, especially N.Nvt since he's using SEP for a long time, also keep in mind running SEP under managed client and unmanaged client could also provide different protection, thus...the results as well.