I thought it might be useful posting up the diameter of the japanese PE lines versus one of the most popular American braids on the market, Western Filaments TF XP. We've always been led to believe that the Japanese PE lines are of a finer diameter than the other braids for the same breaking strain. TF XP has, however, generally tested close to its stated breaking strain. I've also been more inclined to think that the Japanese braids probably break around what is clainmd whereas it is as well known fact that most braids break well above their stated break strains.
The PE diameters below were listed by Greg Burt in another post some time back and are an estimate. PE diameters apparently can also vary from manufacturer to manufacturer.
That said, I think it is quite apparent that the differences in diameters are miniscule, especially once you get to 100lb and above. All of that said, the casting qualities of a line are not just based on its diameter. Varivas GT feels as smooth as slik when you're casting whereas the heavier diameters of TF XP feel quite waxy. TF XP though can be softened by using the Varivas line conditioner on it.
PE DiametersWestern Filament TF XP
65lb - .016"
80lb - .018"
100lb - .019"
130lb - .022"
150lb - .023"
200lb - .028"