Looking at my used stamps in this set, I find a number of them appear to be on what I would call hi-brite paper, but not all. Looking at them closer, I remembered that this set is part of actually three (some would say 5?) issues commemorating the 11th Asian Games: J151, J165, J172, J172M, and J172 S/S
I wonder if there were any differences in printing?
I will be working on these more as time allows and would appreciate any input from others.
Not sure you need to go to that much trouble. Besides, I got some confusing results.
In natural light, there are definite differences in the paper. On a block of 4 mint 4 fen Scott PRC 2295, Yang J394 you can see the 4 fen paper is whiter and brighter than a block of 4 of the 30 fen Scott 2299, Yang J398 with a bluish tint, both front and back. As a matter of fact, if you look in the new CS catalogue, the photograph of this set appears to show the same! The 30 fen stamp is "duller" than the others. And after looking there, I went back to my Yang, and sure enough I think I can see those same differences in the Yang photos too.
I see no differences in the Souvenir Sheet stamp paper, so assume without looking that these differences are in the sheet stamps.
So far I find no differences in the J165 stamp set, but have to admit I have far fewer of these to look at, both mint and used.
Note that not all of the 4 fen stamps are on the whiter paper. But all of the 30 fen stamps so far appear to be on the "duller", or "bluish" paper.