Liston uses his superior boxing ability and ring IQ to outjab Foreman and break him down en route to a midround stoppage.
I was reading about Foreman and Liston yesterday. Foreman really worshipped the guy. "I wanted to be him. In the ring. I tried to take a step into his footprints. In the ring." I'm not sure, to be honest, that this level of hero worship (prime for prime) can be overcome in combat. But I'm not saying that it proves Liston a better fighter or anything (I think he is, but it's besides the point) but it's as good a reason for picking a fighter as any other.
I just watched a foreman documentary last night and he said that exact thing, that after he won the title, he was trying to imitate Sonny in demeanor, intensity, etc. I agree, it would be hard to try to go 100% against your idol. It would be like going against your older brother, or something. Always that respect. Could make the difference, as you said.
Foreman had a lot to say about Liston in sparring as well, saying it was "the most dangerous thing he ever did" and called him "the perfect package". I actually saw a couple seconds of them shadowboxing in a video recently.
Liston has the better jab. Foreman had the better chin. Who hit harder is up in the air but I’m inclined to lean towards foreman. Who wins ? Here’s a vote for big George but hardly a forgone conclusion.