The main (and to my mind very significant) difference is the frame. The Comp frame is E5 alum, the Sport A1. The former is lighter, stronger, more thoroughly butted etc, and probably subject to greater quality control. If that matters to you (it would to me), that alone is worth the difference assuming your plan would be to keep the bike long-term.

If not, no point in paying the difference. The components on the Comp are better, but those on the Sport are perfectly functional.

Edit: if it were me, though, I'd not bother with the discs and go with either the Elite or Comp non-disc: E5 frame; carbon fork.