There are a lot more differences between SR & NR than the obvious ones. The hidden and hard to find parts that owners who claim to have full SR groupsets ignore are where the real differences occur. In fact there are SR bottom brackets and there was a specific SR headset.
There i some interesting info on CampyOnly - http://www.campyonly.com/tipstrivia.html
The only "hidden" difference is the ti bb and pedal axles. Everything else is quite obvious; drilled brake levers, cutaway rings etc.
But the parts did change through the years, eg early SR seatpin was the 2 bolt design with flutes, the one bolt type was later and there were slightly different versions of that as well.
I think the more common SR group would have steel axles instead of ti as there was a feeling that ti was less reliable, plus ti was more expensive.