I think he's a much more focused fighter than Jianliang is and only cares about winning fights. Jianliang often just looks like he's trying to entertain either himself or the crowd. He spends tons of time moving around not doing much and then throwing some sort of flashy kick. I think Jianliang can do fundamental stuff just as well as Rui can and is much more athletic, but doesn't seem to have much use for it a lot of the time.
I've seen footage of both of them training and Jianliang looks much better than Rui: he's faster, he hits harder, he's much more explosive, he's better balanced, etc. But I don't think he's as disciplined as Rui.