Public speaking is a learned skill and to do it well, you need to do a few things that you wouldn't necessarily do in face to face conversation. I don't think it's the greatest way to judge what someone is like because a lot of nuance has to be cut from the content and your personality to appeal to a larger audience.
From the short conversations and limited interactions I've had with each of them plus Sam's actions since becoming president (eg http://blog.samaltman.com/what-ive-learned-from-female-found... and his recent RFS for breakthrough technologies) it seems to me that their leadership styles are very, very different.