The stand alone 3Delight is the version of the renderer that isn’t connected with Studio. The version of 3Delight included in DS4.5 is ‘unlocked’, meaning it can use as many cores as your computer has (in your case that would be 4…well, 8, because your i7 has 4 physical cores and 4 ‘virtual’ cores). So, it would seem like it would be a lot slower to use, but because it is running without the overhead of DS 4.5 it can do the same job more efficiently…and nearly or in some cases, faster.
It also allows you to ‘free up’ DS4.5 for other things while rendering.
Using it, though, is considered an ‘advanced technique’.