First of all the comparison and creation of theoretical sex neutrality. She started on the legendary male side and him on the female side to create a gender unbiased relation. His side was flatter and in more desert. Her side was in the mountains and started in the pristine tourist area.
She was cooperative and moved smoothly with her guides just like the smooth curves of her side of the wall. He did not cooperate as smoothly he wanted things his way or no way, leading to the no way side. Her path was far more rocky because she chose to walk on the wall, she wanted to take the path build not the one beside it as he did.
Her concept was not to plan but to rather go with the flow. Whatever happened happened, she even tracked backwards once. He has a map and stuck to a plan. He though about what was ahead and she didn't. This goes back to their relationship and how much was invested in the project.
Lastly their reuniting was interesting conceptually in the fact that their reactions were different even though they both walked the great wall, both started with the same idea and in the end both wrote the same poem. She cried when they met again and he commented on her shoes, two very different reactions and turned out to be two very different trips.