The difference is those are two seperate brands. I think Hyundai would be well advised to consider making Genesis its premium brand.
while it is possible Hyundai may bend to pressure to do so, i doubt they will, for a couple of reasons...their existing line-up is already well received, so spending $1 Billion+ on a "premium brand" does very little in terms of ROI...let's say they come out with a premium name...the car is the same...instead of the Hyundai Genesis, it is the Proton Genesis (or whatever name they pick)...for starters, anyone buying a premium vehicle for its content and value, is already going to be attracted to the Genesis as it is...those who purchase because of the name on the grill won't get the Hyundai or the Proton anyway, so they won't pick up those customers regardless of what they do...i think Hyundai's current strategy, at least for now, is best...their sales for those two models aren't currently high enough to justify an entirely exclusive name and showroom.
Nah, I think that the reason they aren't selling is because of the lack of a separate brand and sales experience. Say what you will, but Hyundai is known as, and made it's success by being, a very Wal-Mart type of auto purchasing experience. That being, they sold the products people need at a good price. Seeing the great success they have achieved, both Hyundai and Wal-Mart, it is hard to argue with this path.
However, luxury cars are totally unneeded, aspirational choices. They are totally not about what you need but what you want. And, what your choice says about you to your friends, neighbors, coworkers, clients etc.
Just as there is basically nothing you need to buy in clothing from Harry Rosen, let's say, that you can't get from Wal Mart, one is the aspirational choice, while the other is the practical. There is very little you can do from a practical way in a Genesis sedan that you could not do with a Sonata.