What's the Difference between Cobra and Upward Facing Dog

A couple of days ago, my friend asked me what the difference was between these poses: Cobra and Upward Dog. My knee-jerk response was to tell her that it's all in the hand positioning. But, I am not a yoga teacher, and actually wanted to see if there was more to it than I thought. Holy cats, yes there is! OK, kudos to me for knowing that the hand position was indeed different, but there was so much more to these poses that they are truly different poses, even though on the outside they look the same.

Cobra Pose

Upward Dog Pose

This youtube video is so succinct in explaining the difference. I felt that I had to share with everyone. Those of you who thought the same thing as me--this video is for you. Enjoy! http://www.youtube.com/watch?v=zt5p4rv6oWo