Some of the Raleigh experts can answer better than me. Raleigh bought Carlton, and (correct me if I'm wrong, Raleigh experts) for a time produced both Raleighs and Carltons. That ownership led to the use of Carlton's wrap-around seat stay treatment on the Grand Prix. Thus, this frameset is either a Raleigh Grand Prix or a Carlton.

The Grand Prix should be hi-ten tubing. Not sure about Carlton.

Taking a wild guess, I'd say Carlton is not as common, therefore more desirable. Just a guess, I'm not sure if one or the other is better. Again, the experts will know.