Keitel has much more room, and his scenes have way more interaction, and feature a dead body, which adds a LOT more drama.
Walkens had to create all of his drama on his own, just sitting opposite a ***. He has a much deeper (Pun intended) impact for the young man, growing up. A classic example of such scenes, everyone of us has experience such a scene or two, probably not with some clock from your dead *****'s buddy's ass. But then again, maybe your story is even weirder. Life writes some pretty crazy stories.