One would have to look at each bike/brand. Other features are that most brands are trying to specifically add some flex to the endurance bikes.
So, Specialized adds Zerts and the Future Shock in the Roubaix and a few other bikes.
Trek uses IsoSpeed decouplers in critical locations.
Another thing to look at is tire sizes.
Traditionally, many of the road bikes were topping at about 25mm, or perhaps 28mm tire sizes.
At 6'5", how heavy are you? You might find yourself leaning towards 28mm, or perhaps 32mm tires. Anyway, I would certainly put tire clearance as one of the criteria that I'd use with choosing a new bike.