It's confusing I can see. It appears that the one through Dell, the second one, is more expensive as they aren't offering as big a discount. Plus you get less anyway......
It's just a name but if it's anything like the McAfee software that my ISP offers it is merely antivirus and firewall and that's it, whereas the 1st one comes with those 2 plus SiteAdvisor, Anti-Spam and a limted form of Online Backup. Plus it covers up to 3 machines or operating systems.
So for $10 cheaper I'd go for the 1st one anytime.
Here we term the actual user interface that you see when you click the taskbar icon 'SecurityCenter' as it is the vessel that holds all the various components, so for Dell to call theirs SecurityCenter is a bit confusing.
At least my ISP calls their McAfee software 'Web Essentials' which removes any doubt.