I had both a '74 Carlton International and a '78 Super Course at the same time in 1978-1980. The difference in the cosmetic appearance of the brazing that was visible with the paint in place was marked. But it was purely an appearance thing in my opinion, both frames were solid, well built and trouble free. I put a lot of miles on those bikes and enjoyed both a lot. If I could have these two Raleighs and my Bottecchia from 1972 back I would never want for another bike, just do restorations to the best of my abilities and ride them until I dropped.
The International seemed to show more time taken in the brazing than the Super Course lugs had to braze them. Nothing that would make me think about any failure at the lug or in the brazing, just the appearance was noticeable. When I stripped the paint off of the International because it was flaking off wholesale (my only complaint about either bike,) I could see that the International had very well executed brazing and lug work compared to the Super Course. I attributed this to the difference in the price level of the two bikes. Mechanically they both were flawless, the Campagnolo on the International was NR and lived up to its reputation, fully. the Super course was Sun Tour with their bar end shifters and it was pretty much the usual workmanlike shifting and braking that never brought attention to itself. I did swap the center pull brakes on the International for some long reach Sun Tour Superbe side pulls, purely youthful desire to "look like the racers" on a great fast club and touring frame.
Sorry for the long winded slobbering down memory lane, these two bike were special to me in many ways.
Bill