Quite a long link for that... Anyway, the specific question is answered as:
Q: What is different between Media Composer 7 and Media Composer 7 with the Symphony Option?
A: Media Composer 7 with the Symphony Option includes the same feature set as previous versions of the Symphony stand-alone software. By adding the Symphony Option to your Media Composer 7 software, you enable Universal Mastering, the full Symphony Color Correction feature set, which includes secondary color correction, and Boris Continuum Complete v8.x.
The ones of interest will be the additional color correction control and Boris Continuum Complete. Symphony Universal Mastering only works with Avid hardware and only with tape based-outputs which may or may not be of interest to you. In color correction, it is the secondary, channel blending, and relational (speed up the process) that will be the biggest difference. And of course BCC comes with it.