I think English and humanity are two good points here. About English, I think Lee's much better understanding of English or western culture probably play an more important role here than just speaking good English. I read a report that Chen can speak fluent English and has a US green card. I really doubt Chen has a good understanding of Enlgish culture at all after I read a report about what he said at a press conference a couple of years ago.
What I want to add to the two good points is I think what makes the difference is probably much deeper and more foundamental than just the two factors. I think what comes down to it is the Lee's maturity - a maturity as a human being, not the maturity for city slicker's sophistication. Let me put it another way: how "high" one can reach is primarily depending on how "low" one can be and has been.