Austin there isn’t a great deal of difference between the two you notice it more when there young but once there mature its difficult to tell them apart, and in the uk there doesn’t appear to of been any difference in hardiness between the two.
Sakhalin basjoo was tested and compared to Ryukku basjoo and there was a difference but only enough to say that they’re different clones, there both still normal basjoo.
Have a look at this
Hardy Tropicals - View topic - Sakhalin Basjoo and normal Basjoo flower