Their throwing mechanics are remarkably similar: quick dropback, shoulders and head remain totally steady, maintain good balance, strong hip rotation into their throws, quick sidearm delivery. Both are skinny QBs, but they're able to generate better-than-expected velocity on their passes using that whiplash throwing motion. Nice touch and excellent accuracy, but their passes tend to sail (especially on crossing and post routes) due to that sidearm delivery. Watching them from a distance, it would be difficult to tell the two players apart.
I like Colt Brennan, despite his physical limitations, because he's got a gunslinger mentality and throws the hell out of that football. If Bradford can display a similar level of instincts and moxie to go along with his better-than-average physical skills, then he'll have a solid career in the NFL. Otherwise, he'll just be another robotic system-QB who struggles to survive in the big leagues.