The way it was explained to me was that the Cascades are built in the Japanese factory and the Arcadias are built in the Chinese factory. The quality is of the prism and glass are supposedly better? There are other companies who do the same thing.
Take this for what it's worth, it came from the sales rep at Cabelas. I was very clear that I was buying the binos elsewhere but he was very willing to talk about them and seemed very knowledgable. I appreciated the time he took talking about them and other various glasses. It all checked out when I researched it online as well.
I have the Cascades and love them. Early morning low light conditions are extremely clear, better than I was expecting.
Not an expert by any stretch of the imagination, just had the same questions...