If you're comparing Peyton to Brady, Peyton was more of a statue . Brady was much better at sensing the pressure and instinctively sliding around in the pocket. Peyton was extremely immobile the last 6 years of his career. Brady is not a blazer by any means, but he was more mobile and has the arm strength to throw on the run. Peyton didn't have the arm strength to throw on the run, especially outdoors. Teams would give him the deep ball knowing Peyton couldn't throw the ball very far in outdoor cold weather. Brady can still throw a nice deep ball even in the conditions.
Peyton was probably the king of getting flustered under pressure. When he got that whipped puppy look, you knew it was over. And the guy was mentally done. Brady has always been more mentally tough, and more calm under pressure. Peyton always had those happy feet and looked like he was scared of contact.
Both were great qb's, but Brady stands head and shoulders above Peyton.